15. Integration Testing

15.1 Overview

It is important to be able to perform some integration testing without requiring deployment to your application server or connecting to other enterprise infrastructure. This will enable you to test things such as:

  • The correct wiring of your Spring IoC container contexts.
  • Data access using JDBC or an ORM tool. This would include such things as the correctness of SQL statements, Hibernate queries, JPA entity mappings, etc.

The Spring Framework provides first-class support for integration testing in the spring-test module. The name of the actual JAR file might include the release version and might also be in the long org.springframework.test form, depending on where you get it from (see the section on Dependency Management for an explanation). This library includes the org.springframework.test package, which contains valuable classes for integration testing with a Spring container. This testing does not rely on an application server or other deployment environment. Such tests are slower to run than unit tests but much faster than the equivalent Selenium tests or remote tests that rely on deployment to an application server.

In Spring 2.5 and later, unit and integration testing support is provided in the form of the annotation-driven Spring TestContext Framework. The TestContext framework is agnostic of the actual testing framework in use, thus allowing instrumentation of tests in various environments including JUnit, TestNG, and so on.

15.2 Goals of Integration Testing

Spring’s integration testing support has the following primary goals:

The next few sections describe each goal and provide links to implementation and configuration details.

15.2.1 Context management and caching

The Spring TestContext Framework provides consistent loading of Spring ApplicationContexts and WebApplicationContexts as well as caching of those contexts. Support for the caching of loaded contexts is important, because startup time can become an issue — not because of the overhead of Spring itself, but because the objects instantiated by the Spring container take time to instantiate. For example, a project with 50 to 100 Hibernate mapping files might take 10 to 20 seconds to load the mapping files, and incurring that cost before running every test in every test fixture leads to slower overall test runs that reduce developer productivity.

Test classes typically declare either an array of resource locations for XML or Groovy configuration metadata — often in the classpath — or an array of annotated classes that is used to configure the application. These locations or classes are the same as or similar to those specified in web.xml or other configuration files for production deployments.

By default, once loaded, the configured ApplicationContext is reused for each test. Thus the setup cost is incurred only once per test suite, and subsequent test execution is much faster. In this context, the term test suite means all tests run in the same JVM — for example, all tests run from an Ant, Maven, or Gradle build for a given project or module. In the unlikely case that a test corrupts the application context and requires reloading — for example, by modifying a bean definition or the state of an application object — the TestContext framework can be configured to reload the configuration and rebuild the application context before executing the next test.

See Section 15.5.4, “Context management” and the section called “Context caching” with the TestContext framework.

15.2.2 Dependency Injection of test fixtures

When the TestContext framework loads your application context, it can optionally configure instances of your test classes via Dependency Injection. This provides a convenient mechanism for setting up test fixtures using preconfigured beans from your application context. A strong benefit here is that you can reuse application contexts across various testing scenarios (e.g., for configuring Spring-managed object graphs, transactional proxies, DataSources, etc.), thus avoiding the need to duplicate complex test fixture setup for individual test cases.

As an example, consider the scenario where we have a class, HibernateTitleRepository, that implements data access logic for a Title domain entity. We want to write integration tests that test the following areas:

  • The Spring configuration: basically, is everything related to the configuration of the HibernateTitleRepository bean correct and present?
  • The Hibernate mapping file configuration: is everything mapped correctly, and are the correct lazy-loading settings in place?
  • The logic of the HibernateTitleRepository: does the configured instance of this class perform as anticipated?

See dependency injection of test fixtures with the TestContext framework.

15.2.3 Transaction management

One common issue in tests that access a real database is their effect on the state of the persistence store. Even when you’re using a development database, changes to the state may affect future tests. Also, many operations — such as inserting or modifying persistent data — cannot be performed (or verified) outside a transaction.

The TestContext framework addresses this issue. By default, the framework will create and roll back a transaction for each test. You simply write code that can assume the existence of a transaction. If you call transactionally proxied objects in your tests, they will behave correctly, according to their configured transactional semantics. In addition, if a test method deletes the contents of selected tables while running within the transaction managed for the test, the transaction will roll back by default, and the database will return to its state prior to execution of the test. Transactional support is provided to a test via a PlatformTransactionManager bean defined in the test’s application context.

If you want a transaction to commit — unusual, but occasionally useful when you want a particular test to populate or modify the database — the TestContext framework can be instructed to cause the transaction to commit instead of roll back via the @Commit annotation.

See transaction management with the TestContext framework.

15.2.4 Support classes for integration testing

The Spring TestContext Framework provides several abstract support classes that simplify the writing of integration tests. These base test classes provide well-defined hooks into the testing framework as well as convenient instance variables and methods, which enable you to access:

  • The ApplicationContext, for performing explicit bean lookups or testing the state of the context as a whole.
  • A JdbcTemplate, for executing SQL statements to query the database. Such queries can be used to confirm database state both prior to and after execution of database-related application code, and Spring ensures that such queries run in the scope of the same transaction as the application code. When used in conjunction with an ORM tool, be sure to avoid false positives.

In addition, you may want to create your own custom, application-wide superclass with instance variables and methods specific to your project.

See support classes for the TestContext framework.

15.3 JDBC Testing Support

The org.springframework.test.jdbc package contains JdbcTestUtils, which is a collection of JDBC related utility functions intended to simplify standard database testing scenarios. Specifically, JdbcTestUtils provides the following static utility methods.

  • countRowsInTable(..): counts the number of rows in the given table
  • countRowsInTableWhere(..): counts the number of rows in the given table, using the provided WHERE clause
  • deleteFromTables(..): deletes all rows from the specified tables
  • deleteFromTableWhere(..): deletes rows from the given table, using the provided WHERE clause
  • dropTables(..): drops the specified tables

Note that AbstractTransactionalJUnit4SpringContextTests and AbstractTransactionalTestNGSpringContextTests provide convenience methods which delegate to the aforementioned methods in JdbcTestUtils.

The spring-jdbc module provides support for configuring and launching an embedded database which can be used in integration tests that interact with a database. For details, see Section 19.8, “Embedded database support” and Section 19.8.5, “Testing data access logic with an embedded database”.

15.4 Annotations

15.4.1 Spring Testing Annotations

The Spring Framework provides the following set of Spring-specific annotations that you can use in your unit and integration tests in conjunction with the TestContext framework. Refer to the corresponding javadocs for further information, including default attribute values, attribute aliases, and so on.

@BootstrapWith

@BootstrapWith is a class-level annotation that is used to configure how the Spring TestContext Framework is bootstrapped. Specifically, @BootstrapWith is used to specify a custom TestContextBootstrapper. Consult the Bootstrapping the TestContext framework section for further details.

@ContextConfiguration

@ContextConfiguration defines class-level metadata that is used to determine how to load and configure an ApplicationContext for integration tests. Specifically, @ContextConfiguration declares the application context resource locations or the annotated classes that will be used to load the context.

Resource locations are typically XML configuration files or Groovy scripts located in the classpath; whereas, annotated classes are typically @Configuration classes. However, resource locations can also refer to files and scripts in the file system, and annotated classes can be component classes, etc.

@ContextConfiguration("/test-config.xml")
public class XmlApplicationContextTests {
    // class body...
}
@ContextConfiguration(classes = TestConfig.class)
public class ConfigClassApplicationContextTests {
    // class body...
}

As an alternative or in addition to declaring resource locations or annotated classes, @ContextConfiguration may be used to declare ApplicationContextInitializer classes.

@ContextConfiguration(initializers = CustomContextIntializer.class)
public class ContextInitializerTests {
    // class body...
}

@ContextConfiguration may optionally be used to declare the ContextLoader strategy as well. Note, however, that you typically do not need to explicitly configure the loader since the default loader supports either resource locations or annotated classes as well as initializers.

@ContextConfiguration(locations = "/test-context.xml", loader = CustomContextLoader.class)
public class CustomLoaderXmlApplicationContextTests {
    // class body...
}
[Note]Note

@ContextConfiguration provides support for inheriting resource locations or configuration classes as well as context initializers declared by superclasses by default.

See Section 15.5.4, “Context management” and the @ContextConfiguration javadocs for further details.

@WebAppConfiguration

@WebAppConfiguration is a class-level annotation that is used to declare that the ApplicationContext loaded for an integration test should be a WebApplicationContext. The mere presence of @WebAppConfiguration on a test class ensures that a WebApplicationContext will be loaded for the test, using the default value of "file:src/main/webapp" for the path to the root of the web application (i.e., the resource base path). The resource base path is used behind the scenes to create a MockServletContext which serves as the ServletContext for the test’s WebApplicationContext.

@ContextConfiguration
@WebAppConfiguration
public class WebAppTests {
    // class body...
}

To override the default, specify a different base resource path via the implicit value attribute. Both classpath: and file: resource prefixes are supported. If no resource prefix is supplied the path is assumed to be a file system resource.

@ContextConfiguration
@WebAppConfiguration("classpath:test-web-resources")
public class WebAppTests {
    // class body...
}

Note that @WebAppConfiguration must be used in conjunction with @ContextConfiguration, either within a single test class or within a test class hierarchy. See the @WebAppConfiguration javadocs for further details.

@ContextHierarchy

@ContextHierarchy is a class-level annotation that is used to define a hierarchy of ApplicationContexts for integration tests. @ContextHierarchy should be declared with a list of one or more @ContextConfiguration instances, each of which defines a level in the context hierarchy. The following examples demonstrate the use of @ContextHierarchy within a single test class; however, @ContextHierarchy can also be used within a test class hierarchy.

@ContextHierarchy({
    @ContextConfiguration("/parent-config.xml"),
    @ContextConfiguration("/child-config.xml")
})
public class ContextHierarchyTests {
    // class body...
}
@WebAppConfiguration
@ContextHierarchy({
    @ContextConfiguration(classes = AppConfig.class),
    @ContextConfiguration(classes = WebConfig.class)
})
public class WebIntegrationTests {
    // class body...
}

If you need to merge or override the configuration for a given level of the context hierarchy within a test class hierarchy, you must explicitly name that level by supplying the same value to the name attribute in @ContextConfiguration at each corresponding level in the class hierarchy. See the section called “Context hierarchies” and the @ContextHierarchy javadocs for further examples.

@ActiveProfiles

@ActiveProfiles is a class-level annotation that is used to declare which bean definition profiles should be active when loading an ApplicationContext for an integration test.

@ContextConfiguration
@ActiveProfiles("dev")
public class DeveloperTests {
    // class body...
}
@ContextConfiguration
@ActiveProfiles({"dev", "integration"})
public class DeveloperIntegrationTests {
    // class body...
}
[Note]Note

@ActiveProfiles provides support for inheriting active bean definition profiles declared by superclasses by default. It is also possible to resolve active bean definition profiles programmatically by implementing a custom ActiveProfilesResolver and registering it via the resolver attribute of @ActiveProfiles.

See the section called “Context configuration with environment profiles” and the @ActiveProfiles javadocs for examples and further details.

@TestPropertySource

@TestPropertySource is a class-level annotation that is used to configure the locations of properties files and inlined properties to be added to the set of PropertySources in the Environment for an ApplicationContext loaded for an integration test.

Test property sources have higher precedence than those loaded from the operating system’s environment or Java system properties as well as property sources added by the application declaratively via @PropertySource or programmatically. Thus, test property sources can be used to selectively override properties defined in system and application property sources. Furthermore, inlined properties have higher precedence than properties loaded from resource locations.

The following example demonstrates how to declare a properties file from the classpath.

@ContextConfiguration
@TestPropertySource("/test.properties")
public class MyIntegrationTests {
    // class body...
}

The following example demonstrates how to declare inlined properties.

@ContextConfiguration
@TestPropertySource(properties = { "timezone = GMT", "port: 4242" })
public class MyIntegrationTests {
    // class body...
}

@DirtiesContext

@DirtiesContext indicates that the underlying Spring ApplicationContext has been dirtied during the execution of a test (i.e., modified or corrupted in some manner — for example, by changing the state of a singleton bean) and should be closed. When an application context is marked dirty, it is removed from the testing framework’s cache and closed. As a consequence, the underlying Spring container will be rebuilt for any subsequent test that requires a context with the same configuration metadata.

@DirtiesContext can be used as both a class-level and method-level annotation within the same class or class hierarchy. In such scenarios, the ApplicationContext is marked as dirty before or after any such annotated method as well as before or after the current test class, depending on the configured methodMode and classMode.

The following examples explain when the context would be dirtied for various configuration scenarios:

  • Before the current test class, when declared on a class with class mode set to BEFORE_CLASS.

    @DirtiesContext(classMode = BEFORE_CLASS)
    public class FreshContextTests {
        // some tests that require a new Spring container
    }
  • After the current test class, when declared on a class with class mode set to AFTER_CLASS (i.e., the default class mode).

    @DirtiesContext
    public class ContextDirtyingTests {
        // some tests that result in the Spring container being dirtied
    }
  • Before each test method in the current test class, when declared on a class with class mode set to BEFORE_EACH_TEST_METHOD.

    @DirtiesContext(classMode = BEFORE_EACH_TEST_METHOD)
    public class FreshContextTests {
        // some tests that require a new Spring container
    }
  • After each test method in the current test class, when declared on a class with class mode set to AFTER_EACH_TEST_METHOD.

    @DirtiesContext(classMode = AFTER_EACH_TEST_METHOD)
    public class ContextDirtyingTests {
        // some tests that result in the Spring container being dirtied
    }
  • Before the current test, when declared on a method with the method mode set to BEFORE_METHOD.

    @DirtiesContext(methodMode = BEFORE_METHOD)
    @Test
    public void testProcessWhichRequiresFreshAppCtx() {
        // some logic that requires a new Spring container
    }
  • After the current test, when declared on a method with the method mode set to AFTER_METHOD (i.e., the default method mode).

    @DirtiesContext
    @Test
    public void testProcessWhichDirtiesAppCtx() {
        // some logic that results in the Spring container being dirtied
    }

If @DirtiesContext is used in a test whose context is configured as part of a context hierarchy via @ContextHierarchy, the hierarchyMode flag can be used to control how the context cache is cleared. By default an exhaustive algorithm will be used that clears the context cache including not only the current level but also all other context hierarchies that share an ancestor context common to the current test; all ApplicationContexts that reside in a sub-hierarchy of the common ancestor context will be removed from the context cache and closed. If the exhaustive algorithm is overkill for a particular use case, the simpler current level algorithm can be specified instead, as seen below.

@ContextHierarchy({
    @ContextConfiguration("/parent-config.xml"),
    @ContextConfiguration("/child-config.xml")
})
public class BaseTests {
    // class body...
}

public class ExtendedTests extends BaseTests {

    @Test
    @DirtiesContext(hierarchyMode = CURRENT_LEVEL)
    public void test() {
        // some logic that results in the child context being dirtied
    }
}

For further details regarding the EXHAUSTIVE and CURRENT_LEVEL algorithms see the DirtiesContext.HierarchyMode javadocs.

@TestExecutionListeners

@TestExecutionListeners defines class-level metadata for configuring the TestExecutionListener implementations that should be registered with the TestContextManager. Typically, @TestExecutionListeners is used in conjunction with @ContextConfiguration.

@ContextConfiguration
@TestExecutionListeners({CustomTestExecutionListener.class, AnotherTestExecutionListener.class})
public class CustomTestExecutionListenerTests {
    // class body...
}

@TestExecutionListeners supports inherited listeners by default. See the javadocs for an example and further details.

@Commit

@Commit indicates that the transaction for a transactional test method should be committed after the test method has completed. @Commit can be used as a direct replacement for @Rollback(false) in order to more explicitly convey the intent of the code. Analogous to @Rollback, @Commit may also be declared as a class-level or method-level annotation.

@Commit
@Test
public void testProcessWithoutRollback() {
    // ...
}

@Rollback

@Rollback indicates whether the transaction for a transactional test method should be rolled back after the test method has completed. If true, the transaction is rolled back; otherwise, the transaction is committed (see also @Commit). Rollback semantics for integration tests in the Spring TestContext Framework default to true even if @Rollback is not explicitly declared.

When declared as a class-level annotation, @Rollback defines the default rollback semantics for all test methods within the test class hierarchy. When declared as a method-level annotation, @Rollback defines rollback semantics for the specific test method, potentially overriding class-level @Rollback or @Commit semantics.

@Rollback(false)
@Test
public void testProcessWithoutRollback() {
    // ...
}

@BeforeTransaction

@BeforeTransaction indicates that the annotated void method should be executed before a transaction is started for test methods configured to run within a transaction via Spring’s @Transactional annotation. As of Spring Framework 4.3, @BeforeTransaction methods are not required to be public and may be declared on Java 8 based interface default methods.

@BeforeTransaction
void beforeTransaction() {
    // logic to be executed before a transaction is started
}

@AfterTransaction

@AfterTransaction indicates that the annotated void method should be executed after a transaction is ended for test methods configured to run within a transaction via Spring’s @Transactional annotation. As of Spring Framework 4.3, @AfterTransaction methods are not required to be public and may be declared on Java 8 based interface default methods.

@AfterTransaction
void afterTransaction() {
    // logic to be executed after a transaction has ended
}

@Sql

@Sql is used to annotate a test class or test method to configure SQL scripts to be executed against a given database during integration tests.

@Test
@Sql({"/test-schema.sql", "/test-user-data.sql"})
public void userTest {
    // execute code that relies on the test schema and test data
}

See the section called “Executing SQL scripts declaratively with @Sql” for further details.

@SqlConfig

@SqlConfig defines metadata that is used to determine how to parse and execute SQL scripts configured via the @Sql annotation.

@Test
@Sql(
    scripts = "/test-user-data.sql",
    config = @SqlConfig(commentPrefix = "`", separator = "@@")
)
public void userTest {
    // execute code that relies on the test data
}

@SqlGroup

@SqlGroup is a container annotation that aggregates several @Sql annotations. @SqlGroup can be used natively, declaring several nested @Sql annotations, or it can be used in conjunction with Java 8’s support for repeatable annotations, where @Sql can simply be declared several times on the same class or method, implicitly generating this container annotation.

@Test
@SqlGroup({
    @Sql(scripts = "/test-schema.sql", config = @SqlConfig(commentPrefix = "`")),
    @Sql("/test-user-data.sql")
)}
public void userTest {
    // execute code that uses the test schema and test data
}

15.4.2 Standard Annotation Support

The following annotations are supported with standard semantics for all configurations of the Spring TestContext Framework. Note that these annotations are not specific to tests and can be used anywhere in the Spring Framework.

  • @Autowired
  • @Qualifier
  • @Resource (javax.annotation) if JSR-250 is present
  • @ManagedBean (javax.annotation) if JSR-250 is present
  • @Inject (javax.inject) if JSR-330 is present
  • @Named (javax.inject) if JSR-330 is present
  • @PersistenceContext (javax.persistence) if JPA is present
  • @PersistenceUnit (javax.persistence) if JPA is present
  • @Required
  • @Transactional
[Note]JSR-250 Lifecycle Annotations

In the Spring TestContext Framework @PostConstruct and @PreDestroy may be used with standard semantics on any application components configured in the ApplicationContext; however, these lifecycle annotations have limited usage within an actual test class.

If a method within a test class is annotated with @PostConstruct, that method will be executed before any before methods of the underlying test framework (e.g., methods annotated with JUnit 4’s @Before), and that will apply for every test method in the test class. On the other hand, if a method within a test class is annotated with @PreDestroy, that method will never be executed. Within a test class it is therefore recommended to use test lifecycle callbacks from the underlying test framework instead of @PostConstruct and @PreDestroy.

15.4.3 Spring JUnit 4 Testing Annotations

The following annotations are only supported when used in conjunction with the SpringRunner, Spring’s JUnit rules, or Spring’s JUnit 4 support classes.

@IfProfileValue

@IfProfileValue indicates that the annotated test is enabled for a specific testing environment. If the configured ProfileValueSource returns a matching value for the provided name, the test is enabled. Otherwise, the test will be disabled and effectively ignored.

@IfProfileValue can be applied at the class level, the method level, or both. Class-level usage of @IfProfileValue takes precedence over method-level usage for any methods within that class or its subclasses. Specifically, a test is enabled if it is enabled both at the class level and at the method level; the absence of @IfProfileValue means the test is implicitly enabled. This is analogous to the semantics of JUnit 4’s @Ignore annotation, except that the presence of @Ignore always disables a test.

@IfProfileValue(name="java.vendor", value="Oracle Corporation")
@Test
public void testProcessWhichRunsOnlyOnOracleJvm() {
    // some logic that should run only on Java VMs from Oracle Corporation
}

Alternatively, you can configure @IfProfileValue with a list of values (with OR semantics) to achieve TestNG-like support for test groups in a JUnit 4 environment. Consider the following example:

@IfProfileValue(name="test-groups", values={"unit-tests", "integration-tests"})
@Test
public void testProcessWhichRunsForUnitOrIntegrationTestGroups() {
    // some logic that should run only for unit and integration test groups
}

@ProfileValueSourceConfiguration

@ProfileValueSourceConfiguration is a class-level annotation that specifies what type of ProfileValueSource to use when retrieving profile values configured through the @IfProfileValue annotation. If @ProfileValueSourceConfiguration is not declared for a test, SystemProfileValueSource is used by default.

@ProfileValueSourceConfiguration(CustomProfileValueSource.class)
public class CustomProfileValueSourceTests {
    // class body...
}

@Timed

@Timed indicates that the annotated test method must finish execution in a specified time period (in milliseconds). If the text execution time exceeds the specified time period, the test fails.

The time period includes execution of the test method itself, any repetitions of the test (see @Repeat), as well as any set up or tear down of the test fixture.

@Timed(millis=1000)
public void testProcessWithOneSecondTimeout() {
    // some logic that should not take longer than 1 second to execute
}

Spring’s @Timed annotation has different semantics than JUnit 4’s @Test(timeout=…​) support. Specifically, due to the manner in which JUnit 4 handles test execution timeouts (that is, by executing the test method in a separate Thread), @Test(timeout=…​) preemptively fails the test if the test takes too long. Spring’s @Timed, on the other hand, does not preemptively fail the test but rather waits for the test to complete before failing.

@Repeat

@Repeat indicates that the annotated test method must be executed repeatedly. The number of times that the test method is to be executed is specified in the annotation.

The scope of execution to be repeated includes execution of the test method itself as well as any set up or tear down of the test fixture.

@Repeat(10)
@Test
public void testProcessRepeatedly() {
    // ...
}

15.4.4 Meta-Annotation Support for Testing

It is possible to use most test-related annotations as meta-annotations in order to create custom composed annotations and reduce configuration duplication across a test suite.

Each of the following may be used as meta-annotations in conjunction with the TestContext framework.

  • @BootstrapWith
  • @ContextConfiguration
  • @ContextHierarchy
  • @ActiveProfiles
  • @TestPropertySource
  • @DirtiesContext
  • @WebAppConfiguration
  • @TestExecutionListeners
  • @Transactional
  • @BeforeTransaction
  • @AfterTransaction
  • @Commit
  • @Rollback
  • @Sql
  • @SqlConfig
  • @SqlGroup
  • @Repeat
  • @Timed
  • @IfProfileValue
  • @ProfileValueSourceConfiguration

For example, if we discover that we are repeating the following configuration across our JUnit 4 based test suite…​

@RunWith(SpringRunner.class)
@ContextConfiguration({"/app-config.xml", "/test-data-access-config.xml"})
@ActiveProfiles("dev")
@Transactional
public class OrderRepositoryTests { }

@RunWith(SpringRunner.class)
@ContextConfiguration({"/app-config.xml", "/test-data-access-config.xml"})
@ActiveProfiles("dev")
@Transactional
public class UserRepositoryTests { }

We can reduce the above duplication by introducing a custom composed annotation that centralizes the common test configuration like this:

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@ContextConfiguration({"/app-config.xml", "/test-data-access-config.xml"})
@ActiveProfiles("dev")
@Transactional
public @interface TransactionalDevTest { }

Then we can use our custom @TransactionalDevTest annotation to simplify the configuration of individual test classes as follows:

@RunWith(SpringRunner.class)
@TransactionalDevTest
public class OrderRepositoryTests { }

@RunWith(SpringRunner.class)
@TransactionalDevTest
public class UserRepositoryTests { }

For further details, consult the Spring Annotation Programming Model.

15.5 Spring TestContext Framework

The Spring TestContext Framework (located in the org.springframework.test.context package) provides generic, annotation-driven unit and integration testing support that is agnostic of the testing framework in use. The TestContext framework also places a great deal of importance on convention over configuration with reasonable defaults that can be overridden through annotation-based configuration.

In addition to generic testing infrastructure, the TestContext framework provides explicit support for JUnit 4 and TestNG in the form of abstract support classes. For JUnit 4, Spring also provides a custom JUnit Runner and custom JUnit Rules that allow one to write so-called POJO test classes. POJO test classes are not required to extend a particular class hierarchy.

The following section provides an overview of the internals of the TestContext framework. If you are only interested in using the framework and not necessarily interested in extending it with your own custom listeners or custom loaders, feel free to go directly to the configuration (context management, dependency injection, transaction management), support classes, and annotation support sections.

15.5.1 Key abstractions

The core of the framework consists of the TestContextManager class and the TestContext, TestExecutionListener, and SmartContextLoader interfaces. A TestContextManager is created per test class (e.g., for the execution of all test methods within a single test class in JUnit 4). The TestContextManager in turn manages a TestContext that holds the context of the current test. The TestContextManager also updates the state of the TestContext as the test progresses and delegates to TestExecutionListener implementations, which instrument the actual test execution by providing dependency injection, managing transactions, and so on. A SmartContextLoader is responsible for loading an ApplicationContext for a given test class. Consult the javadocs and the Spring test suite for further information and examples of various implementations.

TestContext

TestContext encapsulates the context in which a test is executed, agnostic of the actual testing framework in use, and provides context management and caching support for the test instance for which it is responsible. The TestContext also delegates to a SmartContextLoader to load an ApplicationContext if requested.

TestContextManager

TestContextManager is the main entry point into the Spring TestContext Framework, which manages a single TestContext and signals events to each registered TestExecutionListener at well-defined test execution points:

  • prior to any before class or before all methods of a particular testing framework
  • test instance post-processing
  • prior to any before or before each methods of a particular testing framework
  • after any after or after each methods of a particular testing framework
  • after any after class or after all methods of a particular testing framework

TestExecutionListener

TestExecutionListener defines the API for reacting to test execution events published by the TestContextManager with which the listener is registered. See Section 15.5.3, “TestExecutionListener configuration”.

Context Loaders

ContextLoader is a strategy interface that was introduced in Spring 2.5 for loading an ApplicationContext for an integration test managed by the Spring TestContext Framework. Implement SmartContextLoader instead of this interface in order to provide support for annotated classes, active bean definition profiles, test property sources, context hierarchies, and WebApplicationContext support.

SmartContextLoader is an extension of the ContextLoader interface introduced in Spring 3.1. The SmartContextLoader SPI supersedes the ContextLoader SPI that was introduced in Spring 2.5. Specifically, a SmartContextLoader can choose to process resource locations, annotated classes, or context initializers. Furthermore, a SmartContextLoader can set active bean definition profiles and test property sources in the context that it loads.

Spring provides the following implementations:

  • DelegatingSmartContextLoader: one of two default loaders which delegates internally to an AnnotationConfigContextLoader, a GenericXmlContextLoader, or a GenericGroovyXmlContextLoader depending either on the configuration declared for the test class or on the presence of default locations or default configuration classes. Groovy support is only enabled if Groovy is on the classpath.
  • WebDelegatingSmartContextLoader: one of two default loaders which delegates internally to an AnnotationConfigWebContextLoader, a GenericXmlWebContextLoader, or a GenericGroovyXmlWebContextLoader depending either on the configuration declared for the test class or on the presence of default locations or default configuration classes. A web ContextLoader will only be used if @WebAppConfiguration is present on the test class. Groovy support is only enabled if Groovy is on the classpath.
  • AnnotationConfigContextLoader: loads a standard ApplicationContext from annotated classes.
  • AnnotationConfigWebContextLoader: loads a WebApplicationContext from annotated classes.
  • GenericGroovyXmlContextLoader: loads a standard ApplicationContext from resource locations that are either Groovy scripts or XML configuration files.
  • GenericGroovyXmlWebContextLoader: loads a WebApplicationContext from resource locations that are either Groovy scripts or XML configuration files.
  • GenericXmlContextLoader: loads a standard ApplicationContext from XML resource locations.
  • GenericXmlWebContextLoader: loads a WebApplicationContext from XML resource locations.
  • GenericPropertiesContextLoader: loads a standard ApplicationContext from Java Properties files.

15.5.2 Bootstrapping the TestContext framework

The default configuration for the internals of the Spring TestContext Framework is sufficient for all common use cases. However, there are times when a development team or third party framework would like to change the default ContextLoader, implement a custom TestContext or ContextCache, augment the default sets of ContextCustomizerFactory and TestExecutionListener implementations, etc. For such low level control over how the TestContext framework operates, Spring provides a bootstrapping strategy.

TestContextBootstrapper defines the SPI for bootstrapping the TestContext framework. A TestContextBootstrapper is used by the TestContextManager to load the TestExecutionListener implementations for the current test and to build the TestContext that it manages. A custom bootstrapping strategy can be configured for a test class (or test class hierarchy) via @BootstrapWith, either directly or as a meta-annotation. If a bootstrapper is not explicitly configured via @BootstrapWith, either the DefaultTestContextBootstrapper or the WebTestContextBootstrapper will be used, depending on the presence of @WebAppConfiguration.

Since the TestContextBootstrapper SPI is likely to change in the future in order to accommodate new requirements, implementers are strongly encouraged not to implement this interface directly but rather to extend AbstractTestContextBootstrapper or one of its concrete subclasses instead.

15.5.3 TestExecutionListener configuration

Spring provides the following TestExecutionListener implementations that are registered by default, exactly in this order.

  • ServletTestExecutionListener: configures Servlet API mocks for a WebApplicationContext
  • DirtiesContextBeforeModesTestExecutionListener: handles the @DirtiesContext annotation for before modes
  • DependencyInjectionTestExecutionListener: provides dependency injection for the test instance
  • DirtiesContextTestExecutionListener: handles the @DirtiesContext annotation for after modes
  • TransactionalTestExecutionListener: provides transactional test execution with default rollback semantics
  • SqlScriptsTestExecutionListener: executes SQL scripts configured via the @Sql annotation

Registering custom TestExecutionListeners

Custom TestExecutionListeners can be registered for a test class and its subclasses via the @TestExecutionListeners annotation. See annotation support and the javadocs for @TestExecutionListeners for details and examples.

Automatic discovery of default TestExecutionListeners

Registering custom TestExecutionListeners via @TestExecutionListeners is suitable for custom listeners that are used in limited testing scenarios; however, it can become cumbersome if a custom listener needs to be used across a test suite. Since Spring Framework 4.1, this issue is addressed via support for automatic discovery of default TestExecutionListener implementations via the SpringFactoriesLoader mechanism.

Specifically, the spring-test module declares all core default TestExecutionListeners under the org.springframework.test.context.TestExecutionListener key in its META-INF/spring.factories properties file. Third-party frameworks and developers can contribute their own TestExecutionListeners to the list of default listeners in the same manner via their own META-INF/spring.factories properties file.

Ordering TestExecutionListeners

When the TestContext framework discovers default TestExecutionListeners via the aforementioned SpringFactoriesLoader mechanism, the instantiated listeners are sorted using Spring’s AnnotationAwareOrderComparator which honors Spring’s Ordered interface and @Order annotation for ordering. AbstractTestExecutionListener and all default TestExecutionListeners provided by Spring implement Ordered with appropriate values. Third-party frameworks and developers should therefore make sure that their default TestExecutionListeners are registered in the proper order by implementing Ordered or declaring @Order. Consult the javadocs for the getOrder() methods of the core default TestExecutionListeners for details on what values are assigned to each core listener.

Merging TestExecutionListeners

If a custom TestExecutionListener is registered via @TestExecutionListeners, the default listeners will not be registered. In most common testing scenarios, this effectively forces the developer to manually declare all default listeners in addition to any custom listeners. The following listing demonstrates this style of configuration.

@ContextConfiguration
@TestExecutionListeners({
    MyCustomTestExecutionListener.class,
    ServletTestExecutionListener.class,
    DirtiesContextBeforeModesTestExecutionListener.class,
    DependencyInjectionTestExecutionListener.class,
    DirtiesContextTestExecutionListener.class,
    TransactionalTestExecutionListener.class,
    SqlScriptsTestExecutionListener.class
})
public class MyTest {
    // class body...
}

The challenge with this approach is that it requires that the developer know exactly which listeners are registered by default. Moreover, the set of default listeners can change from release to release — for example, SqlScriptsTestExecutionListener was introduced in Spring Framework 4.1, and DirtiesContextBeforeModesTestExecutionListener was introduced in Spring Framework 4.2. Furthermore, third-party frameworks like Spring Security register their own default TestExecutionListeners via the aforementioned automatic discovery mechanism.

To avoid having to be aware of and re-declare all default listeners, the mergeMode attribute of @TestExecutionListeners can be set to MergeMode.MERGE_WITH_DEFAULTS. MERGE_WITH_DEFAULTS indicates that locally declared listeners should be merged with the default listeners. The merging algorithm ensures that duplicates are removed from the list and that the resulting set of merged listeners is sorted according to the semantics of AnnotationAwareOrderComparator as described in the section called “Ordering TestExecutionListeners”. If a listener implements Ordered or is annotated with @Order it can influence the position in which it is merged with the defaults; otherwise, locally declared listeners will simply be appended to the list of default listeners when merged.

For example, if the MyCustomTestExecutionListener class in the previous example configures its order value (for example, 500) to be less than the order of the ServletTestExecutionListener (which happens to be 1000), the MyCustomTestExecutionListener can then be automatically merged with the list of defaults in front of the ServletTestExecutionListener, and the previous example could be replaced with the following.

@ContextConfiguration
@TestExecutionListeners(
    listeners = MyCustomTestExecutionListener.class,
    mergeMode = MERGE_WITH_DEFAULTS
)
public class MyTest {
    // class body...
}

15.5.4 Context management

Each TestContext provides context management and caching support for the test instance it is responsible for. Test instances do not automatically receive access to the configured ApplicationContext. However, if a test class implements the ApplicationContextAware interface, a reference to the ApplicationContext is supplied to the test instance. Note that AbstractJUnit4SpringContextTests and AbstractTestNGSpringContextTests implement ApplicationContextAware and therefore provide access to the ApplicationContext automatically.

[Tip]@Autowired ApplicationContext

As an alternative to implementing the ApplicationContextAware interface, you can inject the application context for your test class through the @Autowired annotation on either a field or setter method. For example:

@RunWith(SpringRunner.class)
@ContextConfiguration
public class MyTest {

    @Autowired
    private ApplicationContext applicationContext;

    // class body...
}

Similarly, if your test is configured to load a WebApplicationContext, you can inject the web application context into your test as follows:

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextConfiguration
public class MyWebAppTest {
    @Autowired
    private WebApplicationContext wac;

    // class body...
}

Dependency injection via @Autowired is provided by the DependencyInjectionTestExecutionListener which is configured by default (see Section 15.5.5, “Dependency injection of test fixtures”).

Test classes that use the TestContext framework do not need to extend any particular class or implement a specific interface to configure their application context. Instead, configuration is achieved simply by declaring the @ContextConfiguration annotation at the class level. If your test class does not explicitly declare application context resource locations or annotated classes, the configured ContextLoader determines how to load a context from a default location or default configuration classes. In addition to context resource locations and annotated classes, an application context can also be configured via application context initializers.

The following sections explain how to configure an ApplicationContext via XML configuration files, Groovy scripts, annotated classes (typically @Configuration classes), or context initializers using Spring’s @ContextConfiguration annotation. Alternatively, you can implement and configure your own custom SmartContextLoader for advanced use cases.

Context configuration with XML resources

To load an ApplicationContext for your tests using XML configuration files, annotate your test class with @ContextConfiguration and configure the locations attribute with an array that contains the resource locations of XML configuration metadata. A plain or relative path — for example "context.xml" — will be treated as a classpath resource that is relative to the package in which the test class is defined. A path starting with a slash is treated as an absolute classpath location, for example "/org/example/config.xml". A path which represents a resource URL (i.e., a path prefixed with classpath:, file:, http:, etc.) will be used as is.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from "/app-config.xml" and
// "/test-config.xml" in the root of the classpath
@ContextConfiguration(locations={"/app-config.xml", "/test-config.xml"})
public class MyTest {
    // class body...
}

@ContextConfiguration supports an alias for the locations attribute through the standard Java value attribute. Thus, if you do not need to declare additional attributes in @ContextConfiguration, you can omit the declaration of the locations attribute name and declare the resource locations by using the shorthand format demonstrated in the following example.

@RunWith(SpringRunner.class)
@ContextConfiguration({"/app-config.xml", "/test-config.xml"})
public class MyTest {
    // class body...
}

If you omit both the locations and value attributes from the @ContextConfiguration annotation, the TestContext framework will attempt to detect a default XML resource location. Specifically, GenericXmlContextLoader and GenericXmlWebContextLoader detect a default location based on the name of the test class. If your class is named com.example.MyTest, GenericXmlContextLoader loads your application context from "classpath:com/example/MyTest-context.xml".

package com.example;

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from
// "classpath:com/example/MyTest-context.xml"
@ContextConfiguration
public class MyTest {
    // class body...
}

Context configuration with Groovy scripts

To load an ApplicationContext for your tests using Groovy scripts that utilize the Groovy Bean Definition DSL, annotate your test class with @ContextConfiguration and configure the locations or value attribute with an array that contains the resource locations of Groovy scripts. Resource lookup semantics for Groovy scripts are the same as those described for XML configuration files.

[Tip]Enabling Groovy script support

Support for using Groovy scripts to load an ApplicationContext in the Spring TestContext Framework is enabled automatically if Groovy is on the classpath.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from "/AppConfig.groovy" and
// "/TestConfig.groovy" in the root of the classpath
@ContextConfiguration({"/AppConfig.groovy", "/TestConfig.Groovy"})
public class MyTest {
    // class body...
}

If you omit both the locations and value attributes from the @ContextConfiguration annotation, the TestContext framework will attempt to detect a default Groovy script. Specifically, GenericGroovyXmlContextLoader and GenericGroovyXmlWebContextLoader detect a default location based on the name of the test class. If your class is named com.example.MyTest, the Groovy context loader will load your application context from "classpath:com/example/MyTestContext.groovy".

package com.example;

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from
// "classpath:com/example/MyTestContext.groovy"
@ContextConfiguration
public class MyTest {
    // class body...
}
[Tip]Declaring XML config and Groovy scripts simultaneously

Both XML configuration files and Groovy scripts can be declared simultaneously via the locations or value attribute of @ContextConfiguration. If the path to a configured resource location ends with .xml it will be loaded using an XmlBeanDefinitionReader; otherwise it will be loaded using a GroovyBeanDefinitionReader.

The following listing demonstrates how to combine both in an integration test.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from
// "/app-config.xml" and "/TestConfig.groovy"
@ContextConfiguration({ "/app-config.xml", "/TestConfig.groovy" })
public class MyTest {
    // class body...
}

Context configuration with annotated classes

To load an ApplicationContext for your tests using annotated classes (see Section 7.12, “Java-based container configuration”), annotate your test class with @ContextConfiguration and configure the classes attribute with an array that contains references to annotated classes.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from AppConfig and TestConfig
@ContextConfiguration(classes = {AppConfig.class, TestConfig.class})
public class MyTest {
    // class body...
}
[Tip]Annotated Classes

The term annotated class can refer to any of the following.

  • A class annotated with @Configuration
  • A component (i.e., a class annotated with @Component, @Service, @Repository, etc.)
  • A JSR-330 compliant class that is annotated with javax.inject annotations
  • Any other class that contains @Bean-methods

Consult the javadocs of @Configuration and @Bean for further information regarding the configuration and semantics of annotated classes, paying special attention to the discussion of [email protected]` Lite Mode.

If you omit the classes attribute from the @ContextConfiguration annotation, the TestContext framework will attempt to detect the presence of default configuration classes. Specifically, AnnotationConfigContextLoader and AnnotationConfigWebContextLoader will detect all static nested classes of the test class that meet the requirements for configuration class implementations as specified in the @Configuration javadocs. In the following example, the OrderServiceTest class declares a static nested configuration class named Config that will be automatically used to load the ApplicationContext for the test class. Note that the name of the configuration class is arbitrary. In addition, a test class can contain more than one static nested configuration class if desired.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from the
// static nested Config class
@ContextConfiguration
public class OrderServiceTest {

    @Configuration
    static class Config {

        // this bean will be injected into the OrderServiceTest class
        @Bean
        public OrderService orderService() {
            OrderService orderService = new OrderServiceImpl();
            // set properties, etc.
            return orderService;
        }
    }

    @Autowired
    private OrderService orderService;

    @Test
    public void testOrderService() {
        // test the orderService
    }

}

Mixing XML, Groovy scripts, and annotated classes

It may sometimes be desirable to mix XML configuration files, Groovy scripts, and annotated classes (i.e., typically @Configuration classes) to configure an ApplicationContext for your tests. For example, if you use XML configuration in production, you may decide that you want to use @Configuration classes to configure specific Spring-managed components for your tests, or vice versa.

Furthermore, some third-party frameworks (like Spring Boot) provide first-class support for loading an ApplicationContext from different types of resources simultaneously (e.g., XML configuration files, Groovy scripts, and @Configuration classes). The Spring Framework historically has not supported this for standard deployments. Consequently, most of the SmartContextLoader implementations that the Spring Framework delivers in the spring-test module support only one resource type per test context; however, this does not mean that you cannot use both. One exception to the general rule is that the GenericGroovyXmlContextLoader and GenericGroovyXmlWebContextLoader support both XML configuration files and Groovy scripts simultaneously. Furthermore, third-party frameworks may choose to support the declaration of both locations and classes via @ContextConfiguration, and with the standard testing support in the TestContext framework, you have the following options.

If you want to use resource locations (e.g., XML or Groovy) and @Configuration classes to configure your tests, you will have to pick one as the entry point, and that one will have to include or import the other. For example, in XML or Groovy scripts you can include @Configuration classes via component scanning or define them as normal Spring beans; whereas, in a @Configuration class you can use @ImportResource to import XML configuration files or Groovy scripts. Note that this behavior is semantically equivalent to how you configure your application in production: in production configuration you will define either a set of XML or Groovy resource locations or a set of @Configuration classes that your production ApplicationContext will be loaded from, but you still have the freedom to include or import the other type of configuration.

Context configuration with context initializers

To configure an ApplicationContext for your tests using context initializers, annotate your test class with @ContextConfiguration and configure the initializers attribute with an array that contains references to classes that implement ApplicationContextInitializer. The declared context initializers will then be used to initialize the ConfigurableApplicationContext that is loaded for your tests. Note that the concrete ConfigurableApplicationContext type supported by each declared initializer must be compatible with the type of ApplicationContext created by the SmartContextLoader in use (i.e., typically a GenericApplicationContext). Furthermore, the order in which the initializers are invoked depends on whether they implement Spring’s Ordered interface or are annotated with Spring’s @Order annotation or the standard @Priority annotation.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from TestConfig
// and initialized by TestAppCtxInitializer
@ContextConfiguration(
    classes = TestConfig.class,
    initializers = TestAppCtxInitializer.class)
public class MyTest {
    // class body...
}

It is also possible to omit the declaration of XML configuration files, Groovy scripts, or annotated classes in @ContextConfiguration entirely and instead declare only ApplicationContextInitializer classes which are then responsible for registering beans in the context — for example, by programmatically loading bean definitions from XML files or configuration classes.

@RunWith(SpringRunner.class)
// ApplicationContext will be initialized by EntireAppInitializer
// which presumably registers beans in the context
@ContextConfiguration(initializers = EntireAppInitializer.class)
public class MyTest {
    // class body...
}

Context configuration inheritance

@ContextConfiguration supports boolean inheritLocations and inheritInitializers attributes that denote whether resource locations or annotated classes and context initializers declared by superclasses should be inherited. The default value for both flags is true. This means that a test class inherits the resource locations or annotated classes as well as the context initializers declared by any superclasses. Specifically, the resource locations or annotated classes for a test class are appended to the list of resource locations or annotated classes declared by superclasses. Similarly, the initializers for a given test class will be added to the set of initializers defined by test superclasses. Thus, subclasses have the option of extending the resource locations, annotated classes, or context initializers.

If the inheritLocations or inheritInitializers attribute in @ContextConfiguration is set to false, the resource locations or annotated classes and the context initializers, respectively, for the test class shadow and effectively replace the configuration defined by superclasses.

In the following example that uses XML resource locations, the ApplicationContext for ExtendedTest will be loaded from "base-config.xml" and "extended-config.xml", in that order. Beans defined in "extended-config.xml" may therefore override (i.e., replace) those defined in "base-config.xml".

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from "/base-config.xml"
// in the root of the classpath
@ContextConfiguration("/base-config.xml")
public class BaseTest {
    // class body...
}

// ApplicationContext will be loaded from "/base-config.xml" and
// "/extended-config.xml" in the root of the classpath
@ContextConfiguration("/extended-config.xml")
public class ExtendedTest extends BaseTest {
    // class body...
}

Similarly, in the following example that uses annotated classes, the ApplicationContext for ExtendedTest will be loaded from the BaseConfig and ExtendedConfig classes, in that order. Beans defined in ExtendedConfig may therefore override (i.e., replace) those defined in BaseConfig.

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from BaseConfig
@ContextConfiguration(classes = BaseConfig.class)
public class BaseTest {
    // class body...
}

// ApplicationContext will be loaded from BaseConfig and ExtendedConfig
@ContextConfiguration(classes = ExtendedConfig.class)
public class ExtendedTest extends BaseTest {
    // class body...
}

In the following example that uses context initializers, the ApplicationContext for ExtendedTest will be initialized using BaseInitializer and ExtendedInitializer. Note, however, that the order in which the initializers are invoked depends on whether they implement Spring’s Ordered interface or are annotated with Spring’s @Order annotation or the standard @Priority annotation.

@RunWith(SpringRunner.class)
// ApplicationContext will be initialized by BaseInitializer
@ContextConfiguration(initializers = BaseInitializer.class)
public class BaseTest {
    // class body...
}

// ApplicationContext will be initialized by BaseInitializer
// and ExtendedInitializer
@ContextConfiguration(initializers = ExtendedInitializer.class)
public class ExtendedTest extends BaseTest {
    // class body...
}

Context configuration with environment profiles

Spring 3.1 introduced first-class support in the framework for the notion of environments and profiles (a.k.a., bean definition profiles), and integration tests can be configured to activate particular bean definition profiles for various testing scenarios. This is achieved by annotating a test class with the @ActiveProfiles annotation and supplying a list of profiles that should be activated when loading the ApplicationContext for the test.

[Note]Note

@ActiveProfiles may be used with any implementation of the new SmartContextLoader SPI, but @ActiveProfiles is not supported with implementations of the older ContextLoader SPI.

Let’s take a look at some examples with XML configuration and @Configuration classes.

<!-- app-config.xml -->
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xsi:schemaLocation="...">

    <bean id="transferService"
            class="com.bank.service.internal.DefaultTransferService">
        <constructor-arg ref="accountRepository"/>
        <constructor-arg ref="feePolicy"/>
    </bean>

    <bean id="accountRepository"
            class="com.bank.repository.internal.JdbcAccountRepository">
        <constructor-arg ref="dataSource"/>
    </bean>

    <bean id="feePolicy"
        class="com.bank.service.internal.ZeroFeePolicy"/>

    <beans profile="dev">
        <jdbc:embedded-database id="dataSource">
            <jdbc:script
                location="classpath:com/bank/config/sql/schema.sql"/>
            <jdbc:script
                location="classpath:com/bank/config/sql/test-data.sql"/>
        </jdbc:embedded-database>
    </beans>

    <beans profile="production">
        <jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/datasource"/>
    </beans>

    <beans profile="default">
        <jdbc:embedded-database id="dataSource">
            <jdbc:script
                location="classpath:com/bank/config/sql/schema.sql"/>
        </jdbc:embedded-database>
    </beans>

</beans>
package com.bank.service;

@RunWith(SpringRunner.class)
// ApplicationContext will be loaded from "classpath:/app-config.xml"
@ContextConfiguration("/app-config.xml")
@ActiveProfiles("dev")
public class TransferServiceTest {

    @Autowired
    private TransferService transferService;

    @Test
    public void testTransferService() {
        // test the transferService
    }
}

When TransferServiceTest is run, its ApplicationContext will be loaded from the app-config.xml configuration file in the root of the classpath. If you inspect app-config.xml you’ll notice that the accountRepository bean has a dependency on a dataSource bean; however, dataSource is not defined as a top-level bean. Instead, dataSource is defined three times: in the production profile, the dev profile, and the default profile.

By annotating TransferServiceTest with @ActiveProfiles("dev") we instruct the Spring TestContext Framework to load the ApplicationContext with the active profiles set to {"dev"}. As a result, an embedded database will be created and populated with test data, and the accountRepository bean will be wired with a reference to the development DataSource. And that’s likely what we want in an integration test.

It is sometimes useful to assign beans to a default profile. Beans within the default profile are only included when no other profile is specifically activated. This can be used to define fallback beans to be used in the application’s default state. For example, you may explicitly provide a data source for dev and production profiles, but define an in-memory data source as a default when neither of these is active.

The following code listings demonstrate how to implement the same configuration and integration test but using @Configuration classes instead of XML.

@Configuration
@Profile("dev")
public class StandaloneDataConfig {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.HSQL)
            .addScript("classpath:com/bank/config/sql/schema.sql")
            .addScript("classpath:com/bank/config/sql/test-data.sql")
            .build();
    }
}
@Configuration
@Profile("production")
public class JndiDataConfig {

    @Bean(destroyMethod="")
    public DataSource dataSource() throws Exception {
        Context ctx = new InitialContext();
        return (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
    }
}
@Configuration
@Profile("default")
public class DefaultDataConfig {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.HSQL)
            .addScript("classpath:com/bank/config/sql/schema.sql")
            .build();
    }
}
@Configuration
public class TransferServiceConfig {

    @Autowired DataSource dataSource;

    @Bean
    public TransferService transferService() {
        return new DefaultTransferService(accountRepository(), feePolicy());
    }

    @Bean
    public AccountRepository accountRepository() {
        return new JdbcAccountRepository(dataSource);
    }

    @Bean
    public FeePolicy feePolicy() {
        return new ZeroFeePolicy();
    }

}
package com.bank.service;

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = {
        TransferServiceConfig.class,
        StandaloneDataConfig.class,
        JndiDataConfig.class,
        DefaultDataConfig.class})
@ActiveProfiles("dev")
public class TransferServiceTest {

    @Autowired
    private TransferService transferService;

    @Test
    public void testTransferService() {
        // test the transferService
    }
}

In this variation, we have split the XML configuration into four independent @Configuration classes:

  • TransferServiceConfig: acquires a dataSource via dependency injection using @Autowired
  • StandaloneDataConfig: defines a dataSource for an embedded database suitable for developer tests
  • JndiDataConfig: defines a dataSource that is retrieved from JNDI in a production environment
  • DefaultDataConfig: defines a dataSource for a default embedded database in case no profile is active

As with the XML-based configuration example, we still annotate TransferServiceTest with @ActiveProfiles("dev"), but this time we specify all four configuration classes via the @ContextConfiguration annotation. The body of the test class itself remains completely unchanged.

It is often the case that a single set of profiles is used across multiple test classes within a given project. Thus, to avoid duplicate declarations of the @ActiveProfiles annotation it is possible to declare @ActiveProfiles once on a base class, and subclasses will automatically inherit the @ActiveProfiles configuration from the base class. In the following example, the declaration of @ActiveProfiles (as well as other annotations) has been moved to an abstract superclass, AbstractIntegrationTest.

package com.bank.service;

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = {
        TransferServiceConfig.class,
        StandaloneDataConfig.class,
        JndiDataConfig.class,
        DefaultDataConfig.class})
@ActiveProfiles("dev")
public abstract class AbstractIntegrationTest {
}
package com.bank.service;

// "dev" profile inherited from superclass
public class TransferServiceTest extends AbstractIntegrationTest {

    @Autowired
    private TransferService transferService;

    @Test
    public void testTransferService() {
        // test the transferService
    }
}

@ActiveProfiles also supports an inheritProfiles attribute that can be used to disable the inheritance of active profiles.

package com.bank.service;

// "dev" profile overridden with "production"
@ActiveProfiles(profiles = "production", inheritProfiles = false)
public class ProductionTransferServiceTest extends AbstractIntegrationTest {
    // test body
}

Furthermore, it is sometimes necessary to resolve active profiles for tests programmatically instead of declaratively — for example, based on:

  • the current operating system
  • whether tests are being executed on a continuous integration build server
  • the presence of certain environment variables
  • the presence of custom class-level annotations
  • etc.

To resolve active bean definition profiles programmatically, simply implement a custom ActiveProfilesResolver and register it via the resolver attribute of @ActiveProfiles. The following example demonstrates how to implement and register a custom OperatingSystemActiveProfilesResolver. For further information, refer to the corresponding javadocs.

package com.bank.service;

// "dev" profile overridden programmatically via a custom resolver
@ActiveProfiles(
    resolver = OperatingSystemActiveProfilesResolver.class,
    inheritProfiles = false)
public class TransferServiceTest extends AbstractIntegrationTest {
    // test body
}
package com.bank.service.test;

public class OperatingSystemActiveProfilesResolver implements ActiveProfilesResolver {

    @Override
    String[] resolve(Class<?> testClass) {
        String profile = ...;
        // determine the value of profile based on the operating system
        return new String[] {profile};
    }
}

Context configuration with test property sources

Spring 3.1 introduced first-class support in the framework for the notion of an environment with a hierarchy of property sources, and since Spring 4.1 integration tests can be configured with test-specific property sources. In contrast to the @PropertySource annotation used on @Configuration classes, the @TestPropertySource annotation can be declared on a test class to declare resource locations for test properties files or inlined properties. These test property sources will be added to the set of PropertySources in the Environment for the ApplicationContext loaded for the annotated integration test.

[Note]Note

@TestPropertySource may be used with any implementation of the SmartContextLoader SPI, but @TestPropertySource is not supported with implementations of the older ContextLoader SPI.

Implementations of SmartContextLoader gain access to merged test property source values via the getPropertySourceLocations() and getPropertySourceProperties() methods in MergedContextConfiguration.

Declaring test property sources

Test properties files can be configured via the locations or value attribute of @TestPropertySource as shown in the following example.

Both traditional and XML-based properties file formats are supported — for example, "classpath:/com/example/test.properties" or "file:///path/to/file.xml".

Each path will be interpreted as a Spring Resource. A plain path — for example, "test.properties" — will be treated as a classpath resource that is relative to the package in which the test class is defined. A path starting with a slash will be treated as an absolute classpath resource, for example: "/org/example/test.xml". A path which references a URL (e.g., a path prefixed with classpath:, file:, http:, etc.) will be loaded using the specified resource protocol. Resource location wildcards (e.g. */.properties) are not permitted: each location must evaluate to exactly one .properties or .xml resource.

@ContextConfiguration
@TestPropertySource("/test.properties")
public class MyIntegrationTests {
    // class body...
}

Inlined properties in the form of key-value pairs can be configured via the properties attribute of @TestPropertySource as shown in the following example. All key-value pairs will be added to the enclosing Environment as a single test PropertySource with the highest precedence.

The supported syntax for key-value pairs is the same as the syntax defined for entries in a Java properties file:

  • "key=value"
  • "key:value"
  • "key value"
@ContextConfiguration
@TestPropertySource(properties = {"timezone = GMT", "port: 4242"})
public class MyIntegrationTests {
    // class body...
}

Default properties file detection

If @TestPropertySource is declared as an empty annotation (i.e., without explicit values for the locations or properties attributes), an attempt will be made to detect a default properties file relative to the class that declared the annotation. For example, if the annotated test class is com.example.MyTest, the corresponding default properties file is "classpath:com/example/MyTest.properties". If the default cannot be detected, an IllegalStateException will be thrown.

Precedence

Test property sources have higher precedence than those loaded from the operating system’s environment or Java system properties as well as property sources added by the application declaratively via @PropertySource or programmatically. Thus, test property sources can be used to selectively override properties defined in system and application property sources. Furthermore, inlined properties have higher precedence than properties loaded from resource locations.

In the following example, the timezone and port properties as well as any properties defined in "/test.properties" will override any properties of the same name that are defined in system and application property sources. Furthermore, if the "/test.properties" file defines entries for the timezone and port properties those will be overridden by the inlined properties declared via the properties attribute.

@ContextConfiguration
@TestPropertySource(
    locations = "/test.properties",
    properties = {"timezone = GMT", "port: 4242"}
)
public class MyIntegrationTests {
    // class body...
}

Inheriting and overriding test property sources

@TestPropertySource supports boolean inheritLocations and inheritProperties attributes that denote whether resource locations for properties files and inlined properties declared by superclasses should be inherited. The default value for both flags is true. This means that a test class inherits the locations and inlined properties declared by any superclasses. Specifically, the locations and inlined properties for a test class are appended to the locations and inlined properties declared by superclasses. Thus, subclasses have the option of extending the locations and inlined properties. Note that properties that appear later will shadow (i.e.., override) properties of the same name that appear earlier. In addition, the aforementioned precedence rules apply for inherited test property sources as well.

If the inheritLocations or inheritProperties attribute in @TestPropertySource is set to false, the locations or inlined properties, respectively, for the test class shadow and effectively replace the configuration defined by superclasses.

In the following example, the ApplicationContext for BaseTest will be loaded using only the "base.properties" file as a test property source. In contrast, the ApplicationContext for ExtendedTest will be loaded using the "base.properties" and "extended.properties" files as test property source locations.

@TestPropertySource("base.properties")
@ContextConfiguration
public class BaseTest {
    // ...
}

@TestPropertySource("extended.properties")
@ContextConfiguration
public class ExtendedTest extends BaseTest {
    // ...
}

In the following example, the ApplicationContext for BaseTest will be loaded using only the inlined key1 property. In contrast, the ApplicationContext for ExtendedTest will be loaded using the inlined key1 and key2 properties.

@TestPropertySource(properties = "key1 = value1")
@ContextConfiguration
public class BaseTest {
    // ...
}

@TestPropertySource(properties = "key2 = value2")
@ContextConfiguration
public class ExtendedTest extends BaseTest {
    // ...
}

Loading a WebApplicationContext

Spring 3.2 introduced support for loading a WebApplicationContext in integration tests. To instruct the TestContext framework to load a WebApplicationContext instead of a standard ApplicationContext, simply annotate the respective test class with @WebAppConfiguration.

The presence of @WebAppConfiguration on your test class instructs the TestContext framework (TCF) that a WebApplicationContext (WAC) should be loaded for your integration tests. In the background the TCF makes sure that a MockServletContext is created and supplied to your test’s WAC. By default the base resource path for your MockServletContext will be set to "src/main/webapp". This is interpreted as a path relative to the root of your JVM (i.e., normally the path to your project). If you’re familiar with the directory structure of a web application in a Maven project, you’ll know that "src/main/webapp" is the default location for the root of your WAR. If you need to override this default, simply provide an alternate path to the @WebAppConfiguration annotation (e.g., @WebAppConfiguration("src/test/webapp")). If you wish to reference a base resource path from the classpath instead of the file system, just use Spring’s classpath: prefix.

Please note that Spring’s testing support for WebApplicationContexts is on par with its support for standard ApplicationContexts. When testing with a WebApplicationContext you are free to declare XML configuration files, Groovy scripts, or @Configuration classes via @ContextConfiguration. You are of course also free to use any other test annotations such as @ActiveProfiles, @TestExecutionListeners, @Sql, @Rollback, etc.

The following examples demonstrate some of the various configuration options for loading a WebApplicationContext.

Conventions. 

@RunWith(SpringRunner.class)

// defaults to "file:src/main/webapp"
@WebAppConfiguration

// detects "WacTests-context.xml" in same package
// or static nested @Configuration class
@ContextConfiguration

public class WacTests {
    //...
}

The above example demonstrates the TestContext framework’s support for convention over configuration. If you annotate a test class with @WebAppConfiguration without specifying a resource base path, the resource path will effectively default to "file:src/main/webapp". Similarly, if you declare @ContextConfiguration without specifying resource locations, annotated classes, or context initializers, Spring will attempt to detect the presence of your configuration using conventions (i.e., "WacTests-context.xml" in the same package as the WacTests class or static nested @Configuration classes).

Default resource semantics. 

@RunWith(SpringRunner.class)

// file system resource
@WebAppConfiguration("webapp")

// classpath resource
@ContextConfiguration("/spring/test-servlet-config.xml")

public class WacTests {
    //...
}

This example demonstrates how to explicitly declare a resource base path with @WebAppConfiguration and an XML resource location with @ContextConfiguration. The important thing to note here is the different semantics for paths with these two annotations. By default, @WebAppConfiguration resource paths are file system based; whereas, @ContextConfiguration resource locations are classpath based.

Explicit resource semantics. 

@RunWith(SpringRunner.class)

// classpath resource
@WebAppConfiguration("classpath:test-web-resources")

// file system resource
@ContextConfiguration("file:src/main/webapp/WEB-INF/servlet-config.xml")

public class WacTests {
    //...
}

In this third example, we see that we can override the default resource semantics for both annotations by specifying a Spring resource prefix. Contrast the comments in this example with the previous example.

To provide comprehensive web testing support, Spring 3.2 introduced a ServletTestExecutionListener that is enabled by default. When testing against a WebApplicationContext this TestExecutionListener sets up default thread-local state via Spring Web’s RequestContextHolder before each test method and creates a MockHttpServletRequest, MockHttpServletResponse, and ServletWebRequest based on the base resource path configured via @WebAppConfiguration. ServletTestExecutionListener also ensures that the MockHttpServletResponse and ServletWebRequest can be injected into the test instance, and once the test is complete it cleans up thread-local state.

Once you have a WebApplicationContext loaded for your test you might find that you need to interact with the web mocks — for example, to set up your test fixture or to perform assertions after invoking your web component. The following example demonstrates which mocks can be autowired into your test instance. Note that the WebApplicationContext and MockServletContext are both cached across the test suite; whereas, the other mocks are managed per test method by the ServletTestExecutionListener.

Injecting mocks. 

@WebAppConfiguration
@ContextConfiguration
public class WacTests {

    @Autowired
    WebApplicationContext wac; // cached

    @Autowired
    MockServletContext servletContext; // cached

    @Autowired
    MockHttpSession session;

    @Autowired
    MockHttpServletRequest request;

    @Autowired
    MockHttpServletResponse response;

    @Autowired
    ServletWebRequest webRequest;

    //...
}

Context caching

Once the TestContext framework loads an ApplicationContext (or WebApplicationContext) for a test, that context will be cached and reused for all subsequent tests that declare the same unique context configuration within the same test suite. To understand how caching works, it is important to understand what is meant by unique and test suite.

An ApplicationContext can be uniquely identified by the combination of configuration parameters that are used to load it. Consequently, the unique combination of configuration parameters are used to generate a key under which the context is cached. The TestContext framework uses the following configuration parameters to build the context cache key:

  • locations (from @ContextConfiguration)
  • classes (from @ContextConfiguration)
  • contextInitializerClasses (from @ContextConfiguration)
  • contextCustomizers (from ContextCustomizerFactory)
  • contextLoader (from @ContextConfiguration)
  • parent (from @ContextHierarchy)
  • activeProfiles (from @ActiveProfiles)
  • propertySourceLocations (from @TestPropertySource)
  • propertySourceProperties (from @TestPropertySource)
  • resourceBasePath (from @WebAppConfiguration)

For example, if TestClassA specifies {"app-config.xml", "test-config.xml"} for the locations (or value) attribute of @ContextConfiguration, the TestContext framework will load the corresponding ApplicationContext and store it in a static context cache under a key that is based solely on those locations. So if TestClassB also defines {"app-config.xml", "test-config.xml"} for its locations (either explicitly or implicitly through inheritance) but does not define @WebAppConfiguration, a different ContextLoader, different active profiles, different context initializers, different test property sources, or a different parent context, then the same ApplicationContext will be shared by both test classes. This means that the setup cost for loading an application context is incurred only once (per test suite), and subsequent test execution is much faster.

[Note]Test suites and forked processes

The Spring TestContext framework stores application contexts in a static cache. This means that the context is literally stored in a static variable. In other words, if tests execute in separate processes the static cache will be cleared between each test execution, and this will effectively disable the caching mechanism.

To benefit from the caching mechanism, all tests must run within the same process or test suite. This can be achieved by executing all tests as a group within an IDE. Similarly, when executing tests with a build framework such as Ant, Maven, or Gradle it is important to make sure that the build framework does not fork between tests. For example, if the forkMode for the Maven Surefire plug-in is set to always or pertest, the TestContext framework will not be able to cache application contexts between test classes and the build process will run significantly slower as a result.

Since Spring Framework 4.3, the size of the context cache is bounded with a default maximum size of 32. Whenever the maximum size is reached, a least recently used (LRU) eviction policy is used to evict and close stale contexts. The maximum size can be configured from the command line or a build script by setting a JVM system property named spring.test.context.cache.maxSize. As an alternative, the same property can be set programmatically via the SpringProperties API.

Since having a large number of application contexts loaded within a given test suite can cause the suite to take an unnecessarily long time to execute, it is often beneficial to know exactly how many contexts have been loaded and cached. To view the statistics for the underlying context cache, simply set the log level for the org.springframework.test.context.cache logging category to DEBUG.

In the unlikely case that a test corrupts the application context and requires reloading — for example, by modifying a bean definition or the state of an application object — you can annotate your test class or test method with @DirtiesContext (see the discussion of @DirtiesContext in Section 15.4.1, “Spring Testing Annotations”). This instructs Spring to remove the context from the cache and rebuild the application context before executing the next test. Note that support for the @DirtiesContext annotation is provided by the DirtiesContextBeforeModesTestExecutionListener and the DirtiesContextTestExecutionListener which are enabled by default.

Context hierarchies

When writing integration tests that rely on a loaded Spring ApplicationContext, it is often sufficient to test against a single context; however, there are times when it is beneficial or even necessary to test against a hierarchy of ApplicationContexts. For example, if you are developing a Spring MVC web application you will typically have a root WebApplicationContext loaded via Spring’s ContextLoaderListener and a child WebApplicationContext loaded via Spring’s DispatcherServlet. This results in a parent-child context hierarchy where shared components and infrastructure configuration are declared in the root context and consumed in the child context by web-specific components. Another use case can be found in Spring Batch applications where you often have a parent context that provides configuration for shared batch infrastructure and a child context for the configuration of a specific batch job.

Since Spring Framework 3.2.2, it is possible to write integration tests that use context hierarchies by declaring context configuration via the @ContextHierarchy annotation, either on an individual test class or within a test class hierarchy. If a context hierarchy is declared on multiple classes within a test class hierarchy it is also possible to merge or override the context configuration for a specific, named level in the context hierarchy. When merging configuration for a given level in the hierarchy the configuration resource type (i.e., XML configuration files or annotated classes) must be consistent; otherwise, it is perfectly acceptable to have different levels in a context hierarchy configured using different resource types.

The following JUnit 4 based examples demonstrate common configuration scenarios for integration tests that require the use of context hierarchies.

ControllerIntegrationTests represents a typical integration testing scenario for a Spring MVC web application by declaring a context hierarchy consisting of two levels, one for the root WebApplicationContext (loaded using the TestAppConfig @Configuration class) and one for the dispatcher servlet WebApplicationContext (loaded using the WebConfig @Configuration class). The WebApplicationContext that is autowired into the test instance is the one for the child context (i.e., the lowest context in the hierarchy).

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextHierarchy({
    @ContextConfiguration(classes = TestAppConfig.class),
    @ContextConfiguration(classes = WebConfig.class)
})
public class ControllerIntegrationTests {

    @Autowired
    private WebApplicationContext wac;

    // ...
}

The following test classes define a context hierarchy within a test class hierarchy. AbstractWebTests declares the configuration for a root WebApplicationContext in a Spring-powered web application. Note, however, that AbstractWebTests does not declare @ContextHierarchy; consequently, subclasses of AbstractWebTests can optionally participate in a context hierarchy or simply follow the standard semantics for @ContextConfiguration. SoapWebServiceTests and RestWebServiceTests both extend AbstractWebTests and define a context hierarchy via @ContextHierarchy. The result is that three application contexts will be loaded (one for each declaration of @ContextConfiguration), and the application context loaded based on the configuration in AbstractWebTests will be set as the parent context for each of the contexts loaded for the concrete subclasses.

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextConfiguration("file:src/main/webapp/WEB-INF/applicationContext.xml")
public abstract class AbstractWebTests {}

@ContextHierarchy(@ContextConfiguration("/spring/soap-ws-config.xml")
public class SoapWebServiceTests extends AbstractWebTests {}

@ContextHierarchy(@ContextConfiguration("/spring/rest-ws-config.xml")
public class RestWebServiceTests extends AbstractWebTests {}

The following classes demonstrate the use of named hierarchy levels in order to merge the configuration for specific levels in a context hierarchy. BaseTests defines two levels in the hierarchy, parent and child. ExtendedTests extends BaseTests and instructs the Spring TestContext Framework to merge the context configuration for the child hierarchy level, simply by ensuring that the names declared via the name attribute in @ContextConfiguration are both "child". The result is that three application contexts will be loaded: one for "/app-config.xml", one for "/user-config.xml", and one for {"/user-config.xml", "/order-config.xml"}. As with the previous example, the application context loaded from "/app-config.xml" will be set as the parent context for the contexts loaded from "/user-config.xml" and {"/user-config.xml", "/order-config.xml"}.

@RunWith(SpringRunner.class)
@ContextHierarchy({
    @ContextConfiguration(name = "parent", locations = "/app-config.xml"),
    @ContextConfiguration(name = "child", locations = "/user-config.xml")
})
public class BaseTests {}

@ContextHierarchy(
    @ContextConfiguration(name = "child", locations = "/order-config.xml")
)
public class ExtendedTests extends BaseTests {}

In contrast to the previous example, this example demonstrates how to override the configuration for a given named level in a context hierarchy by setting the inheritLocations flag in @ContextConfiguration to false. Consequently, the application context for ExtendedTests will be loaded only from "/test-user-config.xml" and will have its parent set to the context loaded from "/app-config.xml".

@RunWith(SpringRunner.class)
@ContextHierarchy({
    @ContextConfiguration(name = "parent", locations = "/app-config.xml"),
    @ContextConfiguration(name = "child", locations = "/user-config.xml")
})
public class BaseTests {}

@ContextHierarchy(
    @ContextConfiguration(
        name = "child",
        locations = "/test-user-config.xml",
        inheritLocations = false
))
public class ExtendedTests extends BaseTests {}
[Note]Dirtying a context within a context hierarchy

If @DirtiesContext is used in a test whose context is configured as part of a context hierarchy, the hierarchyMode flag can be used to control how the context cache is cleared. For further details consult the discussion of @DirtiesContext in Spring Testing Annotations and the @DirtiesContext javadocs.

15.5.5 Dependency injection of test fixtures

When you use the DependencyInjectionTestExecutionListener — which is configured by default — the dependencies of your test instances are injected from beans in the application context that you configured with @ContextConfiguration. You may use setter injection, field injection, or both, depending on which annotations you choose and whether you place them on setter methods or fields. For consistency with the annotation support introduced in Spring 2.5 and 3.0, you can use Spring’s @Autowired annotation or the @Inject annotation from JSR 330.

[Tip]Tip

The TestContext framework does not instrument the manner in which a test instance is instantiated. Thus the use of @Autowired or @Inject for constructors has no effect for test classes.

Because @Autowired is used to perform autowiring by type, if you have multiple bean definitions of the same type, you cannot rely on this approach for those particular beans. In that case, you can use @Autowired in conjunction with @Qualifier. As of Spring 3.0 you may also choose to use @Inject in conjunction with @Named. Alternatively, if your test class has access to its ApplicationContext, you can perform an explicit lookup by using (for example) a call to applicationContext.getBean("titleRepository").

If you do not want dependency injection applied to your test instances, simply do not annotate fields or setter methods with @Autowired or @Inject. Alternatively, you can disable dependency injection altogether by explicitly configuring your class with @TestExecutionListeners and omitting DependencyInjectionTestExecutionListener.class from the list of listeners.

Consider the scenario of testing a HibernateTitleRepository class, as outlined in the Goals section. The next two code listings demonstrate the use of @Autowired on fields and setter methods. The application context configuration is presented after all sample code listings.

[Note]Note

The dependency injection behavior in the following code listings is not specific to JUnit 4. The same DI techniques can be used in conjunction with any testing framework.

The following examples make calls to static assertion methods such as assertNotNull() but without prepending the call with Assert. In such cases, assume that the method was properly imported through an import static declaration that is not shown in the example.

The first code listing shows a JUnit 4 based implementation of the test class that uses @Autowired for field injection.

@RunWith(SpringRunner.class)
// specifies the Spring configuration to load for this test fixture
@ContextConfiguration("repository-config.xml")
public class HibernateTitleRepositoryTests {

    // this instance will be dependency injected by type
    @Autowired
    private HibernateTitleRepository titleRepository;

    @Test
    public void findById() {
        Title title = titleRepository.findById(new Long(10));
        assertNotNull(title);
    }
}

Alternatively, you can configure the class to use @Autowired for setter injection as seen below.

@RunWith(SpringRunner.class)
// specifies the Spring configuration to load for this test fixture
@ContextConfiguration("repository-config.xml")
public class HibernateTitleRepositoryTests {

    // this instance will be dependency injected by type
    private HibernateTitleRepository titleRepository;

    @Autowired
    public void setTitleRepository(HibernateTitleRepository titleRepository) {
        this.titleRepository = titleRepository;
    }

    @Test
    public void findById() {
        Title title = titleRepository.findById(new Long(10));
        assertNotNull(title);
    }
}

The preceding code listings use the same XML context file referenced by the @ContextConfiguration annotation (that is, repository-config.xml), which looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- this bean will be injected into the HibernateTitleRepositoryTests class -->
    <bean id="titleRepository" class="com.foo.repository.hibernate.HibernateTitleRepository">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <!-- configuration elided for brevity -->
    </bean>

</beans>
[Note]Note

If you are extending from a Spring-provided test base class that happens to use @Autowired on one of its setter methods, you might have multiple beans of the affected type defined in your application context: for example, multiple DataSource beans. In such a case, you can override the setter method and use the @Qualifier annotation to indicate a specific target bean as follows, but make sure to delegate to the overridden method in the superclass as well.

// ...

    @Autowired
    @Override
    public void setDataSource(@Qualifier("myDataSource") DataSource dataSource) {
        super.setDataSource(dataSource);
    }

// ...

The specified qualifier value indicates the specific DataSource bean to inject, narrowing the set of type matches to a specific bean. Its value is matched against <qualifier> declarations within the corresponding <bean> definitions. The bean name is used as a fallback qualifier value, so you may effectively also point to a specific bean by name there (as shown above, assuming that "myDataSource" is the bean id).

15.5.6 Testing request and session scoped beans

Request and session scoped beans have been supported by Spring since the early years, and since Spring 3.2 it’s a breeze to test your request-scoped and session-scoped beans by following these steps.

  • Ensure that a WebApplicationContext is loaded for your test by annotating your test class with @WebAppConfiguration.
  • Inject the mock request or session into your test instance and prepare your test fixture as appropriate.
  • Invoke your web component that you retrieved from the configured WebApplicationContext (i.e., via dependency injection).
  • Perform assertions against the mocks.

The following code snippet displays the XML configuration for a login use case. Note that the userService bean has a dependency on a request-scoped loginAction bean. Also, the LoginAction is instantiated using SpEL expressions that retrieve the username and password from the current HTTP request. In our test, we will want to configure these request parameters via the mock managed by the TestContext framework.

Request-scoped bean configuration. 

<beans>

    <bean id="userService"
            class="com.example.SimpleUserService"
            c:loginAction-ref="loginAction" />

    <bean id="loginAction" class="com.example.LoginAction"
            c:username="{request.getParameter('user')}"
            c:password="{request.getParameter('pswd')}"
            scope="request">
        <aop:scoped-proxy />
    </bean>

</beans>

In RequestScopedBeanTests we inject both the UserService (i.e., the subject under test) and the MockHttpServletRequest into our test instance. Within our requestScope() test method we set up our test fixture by setting request parameters in the provided MockHttpServletRequest. When the loginUser() method is invoked on our userService we are assured that the user service has access to the request-scoped loginAction for the current MockHttpServletRequest (i.e., the one we just set parameters in). We can then perform assertions against the results based on the known inputs for the username and password.

Request-scoped bean test. 

@RunWith(SpringRunner.class)
@ContextConfiguration
@WebAppConfiguration
public class RequestScopedBeanTests {

    @Autowired UserService userService;
    @Autowired MockHttpServletRequest request;

    @Test
    public void requestScope() {

        request.setParameter("user", "enigma");
        request.setParameter("pswd", "$pr!ng");

        LoginResults results = userService.loginUser();

        // assert results
    }
}

The following code snippet is similar to the one we saw above for a request-scoped bean; however, this time the userService bean has a dependency on a session-scoped userPreferences bean. Note that the UserPreferences bean is instantiated using a SpEL expression that retrieves the theme from the current HTTP session. In our test, we will need to configure a theme in the mock session managed by the TestContext framework.

Session-scoped bean configuration. 

<beans>

    <bean id="userService"
            class="com.example.SimpleUserService"
            c:userPreferences-ref="userPreferences" />

    <bean id="userPreferences"
            class="com.example.UserPreferences"
            c:theme="#{session.getAttribute('theme')}"
            scope="session">
        <aop:scoped-proxy />
    </bean>

</beans>

In SessionScopedBeanTests we inject the UserService and the MockHttpSession into our test instance. Within our sessionScope() test method we set up our test fixture by setting the expected "theme" attribute in the provided MockHttpSession. When the processUserPreferences() method is invoked on our userService we are assured that the user service has access to the session-scoped userPreferences for the current MockHttpSession, and we can perform assertions against the results based on the configured theme.

Session-scoped bean test. 

@RunWith(SpringRunner.class)
@ContextConfiguration
@WebAppConfiguration
public class SessionScopedBeanTests {

    @Autowired UserService userService;
    @Autowired MockHttpSession session;

    @Test
    public void sessionScope() throws Exception {

        session.setAttribute("theme", "blue");

        Results results = userService.processUserPreferences();

        // assert results
    }
}

15.5.7 Transaction management

In the TestContext framework, transactions are managed by the TransactionalTestExecutionListener which is configured by default, even if you do not explicitly declare @TestExecutionListeners on your test class. To enable support for transactions, however, you must configure a PlatformTransactionManager bean in the ApplicationContext that is loaded via @ContextConfiguration semantics (further details are provided below). In addition, you must declare Spring’s @Transactional annotation either at the class or method level for your tests.

Test-managed transactions

Test-managed transactions are transactions that are managed declaratively via the TransactionalTestExecutionListener or programmatically via TestTransaction (see below). Such transactions should not be confused with Spring-managed transactions (i.e., those managed directly by Spring within the ApplicationContext loaded for tests) or application-managed transactions (i.e., those managed programmatically within application code that is invoked via tests). Spring-managed and application-managed transactions will typically participate in test-managed transactions; however, caution should be taken if Spring-managed or application-managed transactions are configured with any propagation type other than REQUIRED or SUPPORTS (see the discussion on transaction propagation for details).

Enabling and disabling transactions

Annotating a test method with @Transactional causes the test to be run within a transaction that will, by default, be automatically rolled back after completion of the test. If a test class is annotated with @Transactional, each test method within that class hierarchy will be run within a transaction. Test methods that are not annotated with @Transactional (at the class or method level) will not be run within a transaction. Furthermore, tests that are annotated with @Transactional but have the propagation type set to NOT_SUPPORTED will not be run within a transaction.

Note that AbstractTransactionalJUnit4SpringContextTests and AbstractTransactionalTestNGSpringContextTests are preconfigured for transactional support at the class level.

The following example demonstrates a common scenario for writing an integration test for a Hibernate-based UserRepository. As explained in the section called “Transaction rollback and commit behavior”, there is no need to clean up the database after the createUser() method is executed since any changes made to the database will be automatically rolled back by the TransactionalTestExecutionListener. See Section 15.7, “PetClinic Example” for an additional example.

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = TestConfig.class)
@Transactional
public class HibernateUserRepositoryTests {

    @Autowired
    HibernateUserRepository repository;

    @Autowired
    SessionFactory sessionFactory;

    JdbcTemplate jdbcTemplate;

    @Autowired
    public void setDataSource(DataSource dataSource) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Test
    public void createUser() {
        // track initial state in test database:
        final int count = countRowsInTable("user");

        User user = new User(...);
        repository.save(user);

        // Manual flush is required to avoid false positive in test
        sessionFactory.getCurrentSession().flush();
        assertNumUsers(count + 1);
    }

    protected int countRowsInTable(String tableName) {
        return JdbcTestUtils.countRowsInTable(this.jdbcTemplate, tableName);
    }

    protected void assertNumUsers(int expected) {
        assertEquals("Number of rows in the [user] table.", expected, countRowsInTable("user"));
    }
}

Transaction rollback and commit behavior

By default, test transactions will be automatically rolled back after completion of the test; however, transactional commit and rollback behavior can be configured declaratively via the @Commit and @Rollback annotations. See the corresponding entries in the annotation support section for further details.

Programmatic transaction management

Since Spring Framework 4.1, it is possible to interact with test-managed transactions programmatically via the static methods in TestTransaction. For example, TestTransaction may be used within test methods, before methods, and after methods to start or end the current test-managed transaction or to configure the current test-managed transaction for rollback or commit. Support for TestTransaction is automatically available whenever the TransactionalTestExecutionListener is enabled.

The following example demonstrates some of the features of TestTransaction. Consult the javadocs for TestTransaction for further details.

@ContextConfiguration(classes = TestConfig.class)
public class ProgrammaticTransactionManagementTests extends
        AbstractTransactionalJUnit4SpringContextTests {

    @Test
    public void transactionalTest() {
        // assert initial state in test database:
        assertNumUsers(2);

        deleteFromTables("user");

        // changes to the database will be committed!
        TestTransaction.flagForCommit();
        TestTransaction.end();
        assertFalse(TestTransaction.isActive());
        assertNumUsers(0);

        TestTransaction.start();
        // perform other actions against the database that will
        // be automatically rolled back after the test completes...
    }

    protected void assertNumUsers(int expected) {
        assertEquals("Number of rows in the [user] table.", expected, countRowsInTable("user"));
    }
}

Executing code outside of a transaction

Occasionally you need to execute certain code before or after a transactional test method but outside the transactional context — for example, to verify the initial database state prior to execution of your test or to verify expected transactional commit behavior after test execution (if the test was configured to commit the transaction). TransactionalTestExecutionListener supports the @BeforeTransaction and @AfterTransaction annotations exactly for such scenarios. Simply annotate any void method in a test class or any void default method in a test interface with one of these annotations, and the TransactionalTestExecutionListener ensures that your before transaction method or after transaction method is executed at the appropriate time.

[Tip]Tip

Any before methods (such as methods annotated with JUnit 4’s @Before) and any after methods (such as methods annotated with JUnit 4’s @After) are executed within a transaction. In addition, methods annotated with @BeforeTransaction or @AfterTransaction are naturally not executed for test methods that are not configured to run within a transaction.

Configuring a transaction manager

TransactionalTestExecutionListener expects a PlatformTransactionManager bean to be defined in the Spring ApplicationContext for the test. In case there are multiple instances of PlatformTransactionManager within the test’s ApplicationContext, a qualifier may be declared via @Transactional("myTxMgr") or @Transactional(transactionManager = "myTxMgr"), or TransactionManagementConfigurer can be implemented by an @Configuration class. Consult the javadocs for TestContextTransactionUtils.retrieveTransactionManager() for details on the algorithm used to look up a transaction manager in the test’s ApplicationContext.

Demonstration of all transaction-related annotations

The following JUnit 4 based example displays a fictitious integration testing scenario highlighting all transaction-related annotations. The example is not intended to demonstrate best practices but rather to demonstrate how these annotations can be used. Consult the annotation support section for further information and configuration examples. Transaction management for @Sql contains an additional example using @Sql for declarative SQL script execution with default transaction rollback semantics.

@RunWith(SpringRunner.class)
@ContextConfiguration
@Transactional(transactionManager = "txMgr")
@Commit
public class FictitiousTransactionalTest {

    @BeforeTransaction
    void verifyInitialDatabaseState() {
        // logic to verify the initial state before a transaction is started
    }

    @Before
    public void setUpTestDataWithinTransaction() {
        // set up test data within the transaction
    }

    @Test
    // overrides the class-level @Commit setting
    @Rollback
    public void modifyDatabaseWithinTransaction() {
        // logic which uses the test data and modifies database state
    }

    @After
    public void tearDownWithinTransaction() {
        // execute "tear down" logic within the transaction
    }

    @AfterTransaction
    void verifyFinalDatabaseState() {
        // logic to verify the final state after transaction has rolled back
    }

}
[Note]Avoid false positives when testing ORM code

When you test application code that manipulates the state of a Hibernate session or JPA persistence context, make sure to flush the underlying unit of work within test methods that execute that code. Failing to flush the underlying unit of work can produce false positives: your test may pass, but the same code throws an exception in a live, production environment. In the following Hibernate-based example test case, one method demonstrates a false positive, and the other method correctly exposes the results of flushing the session. Note that this applies to any ORM frameworks that maintain an in-memory unit of work.

// ...

@Autowired
SessionFactory sessionFactory;

@Transactional
@Test // no expected exception!
public void falsePositive() {
    updateEntityInHibernateSession();
    // False positive: an exception will be thrown once the Hibernate
    // Session is finally flushed (i.e., in production code)
}

@Transactional
@Test(expected = ...)
public void updateWithSessionFlush() {
    updateEntityInHibernateSession();
    // Manual flush is required to avoid false positive in test
    sessionFactory.getCurrentSession().flush();
}

// ...

Or for JPA:

// ...

@PersistenceContext
EntityManager entityManager;

@Transactional
@Test // no expected exception!
public void falsePositive() {
    updateEntityInJpaPersistenceContext();
    // False positive: an exception will be thrown once the JPA
    // EntityManager is finally flushed (i.e., in production code)
}

@Transactional
@Test(expected = ...)
public void updateWithEntityManagerFlush() {
    updateEntityInJpaPersistenceContext();
    // Manual flush is required to avoid false positive in test
    entityManager.flush();
}

// ...

15.5.8 Executing SQL scripts

When writing integration tests against a relational database, it is often beneficial to execute SQL scripts to modify the database schema or insert test data into tables. The spring-jdbc module provides support for initializing an embedded or existing database by executing SQL scripts when the Spring ApplicationContext is loaded. See Section 19.8, “Embedded database support” and Section 19.8.5, “Testing data access logic with an embedded database” for details.

Although it is very useful to initialize a database for testing once when the ApplicationContext is loaded, sometimes it is essential to be able to modify the database during integration tests. The following sections explain how to execute SQL scripts programmatically and declaratively during integration tests.

Executing SQL scripts programmatically

Spring provides the following options for executing SQL scripts programmatically within integration test methods.

  • org.springframework.jdbc.datasource.init.ScriptUtils
  • org.springframework.jdbc.datasource.init.ResourceDatabasePopulator
  • org.springframework.test.context.junit4.AbstractTransactionalJUnit4SpringContextTests
  • org.springframework.test.context.testng.AbstractTransactionalTestNGSpringContextTests

ScriptUtils provides a collection of static utility methods for working with SQL scripts and is mainly intended for internal use within the framework. However, if you require full control over how SQL scripts are parsed and executed, ScriptUtils may suit your needs better than some of the other alternatives described below. Consult the javadocs for individual methods in ScriptUtils for further details.

ResourceDatabasePopulator provides a simple object-based API for programmatically populating, initializing, or cleaning up a database using SQL scripts defined in external resources. ResourceDatabasePopulator provides options for configuring the character encoding, statement separator, comment delimiters, and error handling flags used when parsing and executing the scripts, and each of the configuration options has a reasonable default value. Consult the javadocs for details on default values. To execute the scripts configured in a ResourceDatabasePopulator, you can invoke either the populate(Connection) method to execute the populator against a java.sql.Connection or the execute(DataSource) method to execute the populator against a javax.sql.DataSource. The following example specifies SQL scripts for a test schema and test data, sets the statement separator to "@@", and then executes the scripts against a DataSource.

@Test
public void databaseTest {
    ResourceDatabasePopulator populator = new ResourceDatabasePopulator();
    populator.addScripts(
        new ClassPathResource("test-schema.sql"),
        new ClassPathResource("test-data.sql"));
    populator.setSeparator("@@");
    populator.execute(this.dataSource);
    // execute code that uses the test schema and data
}

Note that ResourceDatabasePopulator internally delegates to ScriptUtils for parsing and executing SQL scripts. Similarly, the executeSqlScript(..) methods in AbstractTransactionalJUnit4SpringContextTests and AbstractTransactionalTestNGSpringContextTests internally use a ResourceDatabasePopulator for executing SQL scripts. Consult the javadocs for the various executeSqlScript(..) methods for further details.

Executing SQL scripts declaratively with @Sql

In addition to the aforementioned mechanisms for executing SQL scripts programmatically, SQL scripts can also be configured declaratively in the Spring TestContext Framework. Specifically, the @Sql annotation can be declared on a test class or test method to configure the resource paths to SQL scripts that should be executed against a given database either before or after an integration test method. Note that method-level declarations override class-level declarations and that support for @Sql is provided by the SqlScriptsTestExecutionListener which is enabled by default.

Path resource semantics

Each path will be interpreted as a Spring Resource. A plain path — for example, "schema.sql" — will be treated as a classpath resource that is relative to the package in which the test class is defined. A path starting with a slash will be treated as an absolute classpath resource, for example: "/org/example/schema.sql". A path which references a URL (e.g., a path prefixed with classpath:, file:, http:, etc.) will be loaded using the specified resource protocol.

The following example demonstrates how to use @Sql at the class level and at the method level within a JUnit 4 based integration test class.

@RunWith(SpringRunner.class)
@ContextConfiguration
@Sql("/test-schema.sql")
public class DatabaseTests {

    @Test
    public void emptySchemaTest {
        // execute code that uses the test schema without any test data
    }

    @Test
    @Sql({"/test-schema.sql", "/test-user-data.sql"})
    public void userTest {
        // execute code that uses the test schema and test data
    }
}

Default script detection

If no SQL scripts are specified, an attempt will be made to detect a default script depending on where @Sql is declared. If a default cannot be detected, an IllegalStateException will be thrown.

  • class-level declaration: if the annotated test class is com.example.MyTest, the corresponding default script is "classpath:com/example/MyTest.sql".
  • method-level declaration: if the annotated test method is named testMethod() and is defined in the class com.example.MyTest, the corresponding default script is "classpath:com/example/MyTest.testMethod.sql".

Declaring multiple @Sql sets

If multiple sets of SQL scripts need to be configured for a given test class or test method but with different syntax configuration, different error handling rules, or different execution phases per set, it is possible to declare multiple instances of @Sql. With Java 8, @Sql can be used as a repeatable annotation. Otherwise, the @SqlGroup annotation can be used as an explicit container for declaring multiple instances of @Sql.

The following example demonstrates the use of @Sql as a repeatable annotation using Java 8. In this scenario the test-schema.sql script uses a different syntax for single-line comments.

@Test
@Sql(scripts = "/test-schema.sql", config = @SqlConfig(commentPrefix = "`"))
@Sql("/test-user-data.sql")
public void userTest {
    // execute code that uses the test schema and test data
}

The following example is identical to the above except that the @Sql declarations are grouped together within @SqlGroup for compatibility with Java 6 and Java 7.

@Test
@SqlGroup({
    @Sql(scripts = "/test-schema.sql", config = @SqlConfig(commentPrefix = "`")),
    @Sql("/test-user-data.sql")
)}
public void userTest {
    // execute code that uses the test schema and test data
}

Script execution phases

By default, SQL scripts will be executed before the corresponding test method. However, if a particular set of scripts needs to be executed after the test method — for example, to clean up database state — the executionPhase attribute in @Sql can be used as seen in the following example. Note that ISOLATED and AFTER_TEST_METHOD are statically imported from Sql.TransactionMode and Sql.ExecutionPhase respectively.

@Test
@Sql(
    scripts = "create-test-data.sql",
    config = @SqlConfig(transactionMode = ISOLATED)
)
@Sql(
    scripts = "delete-test-data.sql",
    config = @SqlConfig(transactionMode = ISOLATED),
    executionPhase = AFTER_TEST_METHOD
)
public void userTest {
    // execute code that needs the test data to be committed
    // to the database outside of the test's transaction
}

Script configuration with @SqlConfig

Configuration for script parsing and error handling can be configured via the @SqlConfig annotation. When declared as a class-level annotation on an integration test class, @SqlConfig serves as global configuration for all SQL scripts within the test class hierarchy. When declared directly via the config attribute of the @Sql annotation, @SqlConfig serves as local configuration for the SQL scripts declared within the enclosing @Sql annotation. Every attribute in @SqlConfig has an implicit default value which is documented in the javadocs of the corresponding attribute. Due to the rules defined for annotation attributes in the Java Language Specification, it is unfortunately not possible to assign a value of null to an annotation attribute. Thus, in order to support overrides of inherited global configuration, @SqlConfig attributes have an explicit default value of either "" for Strings or DEFAULT for Enums. This approach allows local declarations of @SqlConfig to selectively override individual attributes from global declarations of @SqlConfig by providing a value other than "" or DEFAULT. Global @SqlConfig attributes are inherited whenever local @SqlConfig attributes do not supply an explicit value other than "" or DEFAULT. Explicit local configuration therefore overrides global configuration.

The configuration options provided by @Sql and @SqlConfig are equivalent to those supported by ScriptUtils and ResourceDatabasePopulator but are a superset of those provided by the <jdbc:initialize-database/> XML namespace element. Consult the javadocs of individual attributes in @Sql and @SqlConfig for details.

Transaction management for @Sql

By default, the SqlScriptsTestExecutionListener will infer the desired transaction semantics for scripts configured via @Sql. Specifically, SQL scripts will be executed without a transaction, within an existing Spring-managed transaction — for example, a transaction managed by the TransactionalTestExecutionListener for a test annotated with @Transactional — or within an isolated transaction, depending on the configured value of the transactionMode attribute in @SqlConfig and the presence of a PlatformTransactionManager in the test’s ApplicationContext. As a bare minimum however, a javax.sql.DataSource must be present in the test’s ApplicationContext.

If the algorithms used by SqlScriptsTestExecutionListener to detect a DataSource and PlatformTransactionManager and infer the transaction semantics do not suit your needs, you may specify explicit names via the dataSource and transactionManager attributes of @SqlConfig. Furthermore, the transaction propagation behavior can be controlled via the transactionMode attribute of @SqlConfig — for example, if scripts should be executed in an isolated transaction. Although a thorough discussion of all supported options for transaction management with @Sql is beyond the scope of this reference manual, the javadocs for @SqlConfig and SqlScriptsTestExecutionListener provide detailed information, and the following example demonstrates a typical testing scenario using JUnit 4 and transactional tests with @Sql. Note that there is no need to clean up the database after the usersTest() method is executed since any changes made to the database (either within the test method or within the /test-data.sql script) will be automatically rolled back by the TransactionalTestExecutionListener (see transaction management for details).

@RunWith(SpringRunner.class)
@ContextConfiguration(classes = TestDatabaseConfig.class)
@Transactional
public class TransactionalSqlScriptsTests {

    protected JdbcTemplate jdbcTemplate;

    @Autowired
    public void setDataSource(DataSource dataSource) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
    }

    @Test
    @Sql("/test-data.sql")
    public void usersTest() {
        // verify state in test database:
        assertNumUsers(2);
        // execute code that uses the test data...
    }

    protected int countRowsInTable(String tableName) {
        return JdbcTestUtils.countRowsInTable(this.jdbcTemplate, tableName);
    }

    protected void assertNumUsers(int expected) {
        assertEquals("Number of rows in the [user] table.", expected, countRowsInTable("user"));
    }
}

15.5.9 TestContext Framework support classes

Spring JUnit 4 Runner

The Spring TestContext Framework offers full integration with JUnit 4 through a custom runner (supported on JUnit 4.12 or higher). By annotating test classes with @RunWith(SpringJUnit4ClassRunner.class) or the shorter @RunWith(SpringRunner.class) variant, developers can implement standard JUnit 4 based unit and integration tests and simultaneously reap the benefits of the TestContext framework such as support for loading application contexts, dependency injection of test instances, transactional test method execution, and so on. If you would like to use the Spring TestContext Framework with an alternative runner such as JUnit 4’s Parameterized or third-party runners such as the MockitoJUnitRunner, you may optionally use Spring’s support for JUnit rules instead.

The following code listing displays the minimal requirements for configuring a test class to run with the custom Spring Runner. @TestExecutionListeners is configured with an empty list in order to disable the default listeners, which otherwise would require an ApplicationContext to be configured through @ContextConfiguration.

@RunWith(SpringRunner.class)
@TestExecutionListeners({})
public class SimpleTest {

   @Test
   public void testMethod() {
      // execute test logic...
   }
}

Spring JUnit 4 Rules

The org.springframework.test.context.junit4.rules package provides the following JUnit 4 rules (supported on JUnit 4.12 or higher).

  • SpringClassRule
  • SpringMethodRule

SpringClassRule is a JUnit TestRule that supports class-level features of the Spring TestContext Framework; whereas, SpringMethodRule is a JUnit MethodRule that supports instance-level and method-level features of the Spring TestContext Framework.

In contrast to the SpringRunner, Spring’s rule-based JUnit support has the advantage that it is independent of any org.junit.runner.Runner implementation and can therefore be combined with existing alternative runners like JUnit 4’s Parameterized or third-party runners such as the MockitoJUnitRunner.

In order to support the full functionality of the TestContext framework, a SpringClassRule must be combined with a SpringMethodRule. The following example demonstrates the proper way to declare these rules in an integration test.

// Optionally specify a non-Spring Runner via @RunWith(...)
@ContextConfiguration
public class IntegrationTest {

   @ClassRule
   public static final SpringClassRule SPRING_CLASS_RULE = new SpringClassRule();

   @Rule
   public final SpringMethodRule springMethodRule = new SpringMethodRule();

   @Test
   public void testMethod() {
      // execute test logic...
   }
}

JUnit 4 support classes

The org.springframework.test.context.junit4 package provides the following support classes for JUnit 4 based test cases (supported on JUnit 4.12 or higher).

  • AbstractJUnit4SpringContextTests
  • AbstractTransactionalJUnit4SpringContextTests

AbstractJUnit4SpringContextTests is an abstract base test class that integrates the Spring TestContext Framework with explicit ApplicationContext testing support in a JUnit 4 environment. When you extend AbstractJUnit4SpringContextTests, you can access a protected applicationContext instance variable that can be used to perform explicit bean lookups or to test the state of the context as a whole.

AbstractTransactionalJUnit4SpringContextTests is an abstract transactional extension of AbstractJUnit4SpringContextTests that adds some convenience functionality for JDBC access. This class expects a javax.sql.DataSource bean and a PlatformTransactionManager bean to be defined in the ApplicationContext. When you extend AbstractTransactionalJUnit4SpringContextTests you can access a protected jdbcTemplate instance variable that can be used to execute SQL statements to query the database. Such queries can be used to confirm database state both prior to and after execution of database-related application code, and Spring ensures that such queries run in the scope of the same transaction as the application code. When used in conjunction with an ORM tool, be sure to avoid false positives. As mentioned in Section 15.3, “JDBC Testing Support”, AbstractTransactionalJUnit4SpringContextTests also provides convenience methods which delegate to methods in JdbcTestUtils using the aforementioned jdbcTemplate. Furthermore, AbstractTransactionalJUnit4SpringContextTests provides an executeSqlScript(..) method for executing SQL scripts against the configured DataSource.

[Tip]Tip

These classes are a convenience for extension. If you do not want your test classes to be tied to a Spring-specific class hierarchy, you can configure your own custom test classes by using @RunWith(SpringRunner.class) or Spring’s JUnit rules.

TestNG support classes

The org.springframework.test.context.testng package provides the following support classes for TestNG based test cases.

  • AbstractTestNGSpringContextTests
  • AbstractTransactionalTestNGSpringContextTests

AbstractTestNGSpringContextTests is an abstract base test class that integrates the Spring TestContext Framework with explicit ApplicationContext testing support in a TestNG environment. When you extend AbstractTestNGSpringContextTests, you can access a protected applicationContext instance variable that can be used to perform explicit bean lookups or to test the state of the context as a whole.

AbstractTransactionalTestNGSpringContextTests is an abstract transactional extension of AbstractTestNGSpringContextTests that adds some convenience functionality for JDBC access. This class expects a javax.sql.DataSource bean and a PlatformTransactionManager bean to be defined in the ApplicationContext. When you extend AbstractTransactionalTestNGSpringContextTests you can access a protected jdbcTemplate instance variable that can be used to execute SQL statements to query the database. Such queries can be used to confirm database state both prior to and after execution of database-related application code, and Spring ensures that such queries run in the scope of the same transaction as the application code. When used in conjunction with an ORM tool, be sure to avoid false positives. As mentioned in Section 15.3, “JDBC Testing Support”, AbstractTransactionalTestNGSpringContextTests also provides convenience methods which delegate to methods in JdbcTestUtils using the aforementioned jdbcTemplate. Furthermore, AbstractTransactionalTestNGSpringContextTests provides an executeSqlScript(..) method for executing SQL scripts against the configured DataSource.

[Tip]Tip

These classes are a convenience for extension. If you do not want your test classes to be tied to a Spring-specific class hierarchy, you can configure your own custom test classes by using @ContextConfiguration, @TestExecutionListeners, and so on, and by manually instrumenting your test class with a TestContextManager. See the source code of AbstractTestNGSpringContextTests for an example of how to instrument your test class.

15.6 Spring MVC Test Framework

The Spring MVC Test framework provides first class support for testing Spring MVC code using a fluent API that can be used with JUnit, TestNG, or any other testing framework. It’s built on the Servlet API mock objects from the spring-test module and hence does not use a running Servlet container. It uses the DispatcherServlet to provide full Spring MVC runtime behavior and provides support for loading actual Spring configuration with the TestContext framework in addition to a standalone mode in which controllers may be instantiated manually and tested one at a time.

Spring MVC Test also provides client-side support for testing code that uses the RestTemplate. Client-side tests mock the server responses and also do not use a running server.

[Tip]Tip

Spring Boot provides an option to write full, end-to-end integration tests that include a running server. If this is your goal please have a look at the Spring Boot reference page. For more information on the differences between out-of-container and end-to-end integration tests, see the section called “Differences between Out-of-Container and End-to-End Integration Tests”.

15.6.1 Server-Side Tests

It’s easy to write a plain unit test for a Spring MVC controller using JUnit or TestNG: simply instantiate the controller, inject it with mocked or stubbed dependencies, and call its methods passing MockHttpServletRequest, MockHttpServletResponse, etc., as necessary. However, when writing such a unit test, much remains untested: for example, request mappings, data binding, type conversion, validation, and much more. Furthermore, other controller methods such as @InitBinder, @ModelAttribute, and @ExceptionHandler may also be invoked as part of the request processing lifecycle.

The goal of Spring MVC Test is to provide an effective way for testing controllers by performing requests and generating responses through the actual DispatcherServlet.

Spring MVC Test builds on the familiar "mock" implementations of the Servlet API available in the spring-test module. This allows performing requests and generating responses without the need for running in a Servlet container. For the most part everything should work as it does at runtime with a few notable exceptions as explained in the section called “Differences between Out-of-Container and End-to-End Integration Tests”. Here is a JUnit 4 based example of using Spring MVC Test:

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextConfiguration("test-servlet-context.xml")
public class ExampleTests {

    @Autowired
    private WebApplicationContext wac;

    private MockMvc mockMvc;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
    }

    @Test
    public void getAccount() throws Exception {
        this.mockMvc.perform(get("/accounts/1").accept(MediaType.parseMediaType("application/json;charset=UTF-8")))
            .andExpect(status().isOk())
            .andExpect(content().contentType("application/json"))
            .andExpect(jsonPath("$.name").value("Lee"));
    }

}

The above test relies on the WebApplicationContext support of the TestContext framework for loading Spring configuration from an XML configuration file located in the same package as the test class, but Java-based and Groovy-based configuration are also supported. See these sample tests.

The MockMvc instance is used to perform a GET request to "/accounts/1" and verify that the resulting response has status 200, the content type is "application/json", and the response body has a JSON property called "name" with the value "Lee". The jsonPath syntax is supported through the Jayway JsonPath project. There are lots of other options for verifying the result of the performed request that will be discussed below.

Static Imports

The fluent API in the example above requires a few static imports such as MockMvcRequestBuilders.*, MockMvcResultMatchers.*, and MockMvcBuilders.*. An easy way to find these classes is to search for types matching "MockMvc*". If using Eclipse, be sure to add them as "favorite static members" in the Eclipse preferences under Java → Editor → Content Assist → Favorites. That will allow use of content assist after typing the first character of the static method name. Other IDEs (e.g. IntelliJ) may not require any additional configuration. Just check the support for code completion on static members.

Setup Options

There are two main options for creating an instance of MockMvc. The first is to load Spring MVC configuration through the TestContext framework, which loads the Spring configuration and injects a WebApplicationContext into the test to use to build a MockMvc instance:

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextConfiguration("my-servlet-context.xml")
public class MyWebTests {

    @Autowired
    private WebApplicationContext wac;

    private MockMvc mockMvc;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
    }

    // ...

}

The second is to simply create a controller instance manually without loading Spring configuration. Instead basic default configuration, roughly comparable to that of the MVC JavaConfig or the MVC namespace, is automatically created and can be customized to a degree:

public class MyWebTests {

    private MockMvc mockMvc;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.standaloneSetup(new AccountController()).build();
    }

    // ...

}

Which setup option should you use?

The "webAppContextSetup" loads your actual Spring MVC configuration resulting in a more complete integration test. Since the TestContext framework caches the loaded Spring configuration, it helps keep tests running fast, even as you introduce more tests in your test suite. Furthermore, you can inject mock services into controllers through Spring configuration in order to remain focused on testing the web layer. Here is an example of declaring a mock service with Mockito:

<bean id="accountService" class="org.mockito.Mockito" factory-method="mock">
    <constructor-arg value="org.example.AccountService"/>
</bean>

You can then inject the mock service into the test in order set up and verify expectations:

@RunWith(SpringRunner.class)
@WebAppConfiguration
@ContextConfiguration("test-servlet-context.xml")
public class AccountTests {

    @Autowired
    private WebApplicationContext wac;

    private MockMvc mockMvc;

    @Autowired
    private AccountService accountService;

    // ...

}

The "standaloneSetup" on the other hand is a little closer to a unit test. It tests one controller at a time: the controller can be injected with mock dependencies manually, and it doesn’t involve loading Spring configuration. Such tests are more focused on style and make it easier to see which controller is being tested, whether any specific Spring MVC configuration is required to work, and so on. The "standaloneSetup" is also a very convenient way to write ad-hoc tests to verify specific behavior or to debug an issue.

Just like with any "integration vs. unit testing" debate, there is no right or wrong answer. However, using the "standaloneSetup" does imply the need for additional "webAppContextSetup" tests in order to verify your Spring MVC configuration. Alternatively, you may choose to write all tests with "webAppContextSetup" in order to always test against your actual Spring MVC configuration.

Performing Requests

It’s easy to perform requests using any HTTP method:

mockMvc.perform(post("/hotels/{id}", 42).accept(MediaType.APPLICATION_JSON));

You can also perform file upload requests that internally use MockMultipartHttpServletRequest so that there is no actual parsing of a multipart request but rather you have to set it up:

mockMvc.perform(fileUpload("/doc").file("a1", "ABC".getBytes("UTF-8")));

You can specify query parameters in URI template style:

mockMvc.perform(get("/hotels?foo={foo}", "bar"));

Or you can add Servlet request parameters representing either query of form parameters:

mockMvc.perform(get("/hotels").param("foo", "bar"));

If application code relies on Servlet request parameters and doesn’t check the query string explicitly (as is most often the case) then it doesn’t matter which option you use. Keep in mind however that query params provided with the URI template will be decoded while request parameters provided through the param(…​) method are expected to already be decoded.

In most cases it’s preferable to leave out the context path and the Servlet path from the request URI. If you must test with the full request URI, be sure to set the contextPath and servletPath accordingly so that request mappings will work:

mockMvc.perform(get("/app/main/hotels/{id}").contextPath("/app").servletPath("/main"))

Looking at the above example, it would be cumbersome to set the contextPath and servletPath with every performed request. Instead you can set up default request properties:

public class MyWebTests {

    private MockMvc mockMvc;

    @Before
    public void setup() {
        mockMvc = standaloneSetup(new AccountController())
            .defaultRequest(get("/")
            .contextPath("/app").servletPath("/main")
            .accept(MediaType.APPLICATION_JSON).build();
    }

The above properties will affect every request performed through the MockMvc instance. If the same property is also specified on a given request, it overrides the default value. That is why the HTTP method and URI in the default request don’t matter since they must be specified on every request.

Defining Expectations

Expectations can be defined by appending one or more .andExpect(..) calls after performing a request:

mockMvc.perform(get("/accounts/1")).andExpect(status().isOk());

MockMvcResultMatchers.* provides a number of expectations, some of which are further nested with more detailed expectations.

Expectations fall in two general categories. The first category of assertions verifies properties of the response: for example, the response status, headers, and content. These are the most important results to assert.

The second category of assertions goes beyond the response. These assertions allow one to inspect Spring MVC specific aspects such as which controller method processed the request, whether an exception was raised and handled, what the content of the model is, what view was selected, what flash attributes were added, and so on. They also allow one to inspect Servlet specific aspects such as request and session attributes.

The following test asserts that binding or validation failed:

mockMvc.perform(post("/persons"))
    .andExpect(status().isOk())
    .andExpect(model().attributeHasErrors("person"));

Many times when writing tests, it’s useful to dump the results of the performed request. This can be done as follows, where print() is a static import from MockMvcResultHandlers:

mockMvc.perform(post("/persons"))
    .andDo(print())
    .andExpect(status().isOk())
    .andExpect(model().attributeHasErrors("person"));

As long as request processing does not cause an unhandled exception, the print() method will print all the available result data to System.out. Spring Framework 4.2 introduced a log() method and two additional variants of the print() method, one that accepts an OutputStream and one that accepts a Writer. For example, invoking print(System.err) will print the result data to System.err; while invoking print(myWriter) will print the result data to a custom writer. If you would like to have the result data logged instead of printed, simply invoke the log() method which will log the result data as a single DEBUG message under the org.springframework.test.web.servlet.result logging category.

In some cases, you may want to get direct access to the result and verify something that cannot be verified otherwise. This can be achieved by appending .andReturn() after all other expectations:

MvcResult mvcResult = mockMvc.perform(post("/persons")).andExpect(status().isOk()).andReturn();
// ...

If all tests repeat the same expectations you can set up common expectations once when building the MockMvc instance:

standaloneSetup(new SimpleController())
    .alwaysExpect(status().isOk())
    .alwaysExpect(content().contentType("application/json;charset=UTF-8"))
    .build()

Note that common expectations are always applied and cannot be overridden without creating a separate MockMvc instance.

When JSON response content contains hypermedia links created with Spring HATEOAS, the resulting links can be verified using JsonPath expressions:

mockMvc.perform(get("/people").accept(MediaType.APPLICATION_JSON))
    .andExpect(jsonPath("$.links[?(@.rel == 'self')].href").value("http://localhost:8080/people"));

When XML response content contains hypermedia links created with Spring HATEOAS, the resulting links can be verified using XPath expressions:

Map<String, String> ns = Collections.singletonMap("ns", "http://www.w3.org/2005/Atom");
mockMvc.perform(get("/handle").accept(MediaType.APPLICATION_XML))
    .andExpect(xpath("/person/ns:link[@rel='self'][email protected]", ns).string("http://localhost:8080/people"));

Filter Registrations

When setting up a MockMvc instance, you can register one or more Servlet Filter instances:

mockMvc = standaloneSetup(new PersonController()).addFilters(new CharacterEncodingFilter()).build();

Registered filters will be invoked through via the MockFilterChain from spring-test, and the last filter will delegate to the DispatcherServlet.

Differences between Out-of-Container and End-to-End Integration Tests

As mentioned earlier Spring MVC Test is built on the Servlet API mock objects from the spring-test module and does not use a running Servlet container. Therefore there are some important differences compared to full end-to-end integration tests with an actual client and server running.

The easiest way to think about this is starting with a blank MockHttpServletRequest. Whatever you add to it is what the request will be. Things that may catch you by surprise are that there is no context path by default, no jsessionid cookie, no forwarding, error, or async dispatches, and therefore no actual JSP rendering. Instead, "forwarded" and "redirected" URLs are saved in the MockHttpServletResponse and can be asserted with expectations.

This means if you are using JSPs you can verify the JSP page to which the request was forwarded, but there won’t be any HTML rendered. In other words, the JSP will not be invoked. Note however that all other rendering technologies which don’t rely on forwarding such as Thymeleaf, Freemarker, and Velocity will render HTML to the response body as expected. The same is true for rendering JSON, XML, and other formats via @ResponseBody methods.

Alternatively you may consider the full end-to-end integration testing support from Spring Boot via @WebIntegrationTest. See the Spring Boot reference.

There are pros and cons for each approach. The options provided in Spring MVC Test are different stops on the scale from classic unit testing to full integration testing. To be certain, none of the options in Spring MVC Test fall under the category of classic unit testing, but they are a little closer to it. For example, you can isolate the web layer by injecting mocked services into controllers, in which case you’re testing the web layer only through the DispatcherServlet but with actual Spring configuration, just like you might test the data access layer in isolation from the layers above. Or you can use the standalone setup focusing on one controller at a time and manually providing the configuration required to make it work.

Another important distinction when using Spring MVC Test is that conceptually such tests are on the inside of the server-side so you can check what handler was used, if an exception was handled with a HandlerExceptionResolver, what the content of the model is, what binding errors there were, etc. That means it’s easier to write expectations since the server is not a black box as it is when testing it through an actual HTTP client. This is generally an advantage of classic unit testing, that it’s easier to write, reason about, and debug but does not replace the need for full integration tests. At the same time it’s important not to lose sight of the fact that the response is the most important thing to check. In short, there is room here for multiple styles and strategies of testing even within the same project.

Further Server-Side Test Examples

The framework’s own tests include many sample tests intended to demonstrate how to use Spring MVC Test. Browse these examples for further ideas. Also the spring-mvc-showcase has full test coverage based on Spring MVC Test.

15.6.2 HtmlUnit Integration

Spring provides integration between MockMvc and HtmlUnit. This simplifies performing end-to-end testing when using HTML based views. This integration enables developers to:

  • Easily test HTML pages using tools such as HtmlUnit, WebDriver, & Geb without the need to deploy to a Servlet container
  • Test JavaScript within pages
  • Optionally test using mock services to speed up testing
  • Share logic between in-container end-to-end tests and out-of-container integration tests
[Note]Note

MockMvc works with templating technologies that do not rely on a Servlet Container (e.g., Thymeleaf, Freemarker, Velocity, etc.), but it does not work with JSPs since they rely on the Servlet Container.

Why HtmlUnit Integration?

The most obvious question that comes to mind is, "Why do I need this?". The answer is best found by exploring a very basic sample application. Assume you have a Spring MVC web application that supports CRUD operations on a Message object. The application also supports paging through all messages. How would you go about testing it?

With Spring MVC Test, we can easily test if we are able to create a Message.

MockHttpServletRequestBuilder createMessage = post("/messages/")
	.param("summary", "Spring Rocks")
	.param("text", "In case you didn't know, Spring Rocks!");

mockMvc.perform(createMessage)
	.andExpect(status().is3xxRedirection())
	.andExpect(redirectedUrl("/messages/123"));

What if we want to test our form view that allows us to create the message? For example, assume our form looks like the following snippet:

<form id="messageForm" action="/messages/" method="post">
  <div class="pull-right"><a href="/messages/">Messages</a></div>

  <label for="summary">Summary</label>
  <input type="text" class="required" id="summary" name="summary" value="" />

  <label for="text">Message</label>
  <textarea id="text" name="text"></textarea>

  <div class="form-actions">
	<input type="submit" value="Create" />
  </div>
</form>

How do we ensure that our form will produce the correct request to create a new message? A naive attempt would look like this:

mockMvc.perform(get("/messages/form"))
	.andExpect(xpath("//input[@name='summary']").exists())
	.andExpect(xpath("//textarea[@name='text']").exists());

This test has some obvious drawbacks. If we update our controller to use the parameter message instead of text, our form test would continue to pass even though the HTML form is out of synch with the controller. To resolve this we can combine our two tests.

String summaryParamName = "summary";
String textParamName = "text";
mockMvc.perform(get("/messages/form"))
		.andExpect(xpath("//input[@name='" + summaryParamName + "']").exists())
		.andExpect(xpath("//textarea[@name='" + textParamName + "']").exists());

MockHttpServletRequestBuilder createMessage = post("/messages/")
		.param(summaryParamName, "Spring Rocks")
		.param(textParamName, "In case you didn't know, Spring Rocks!");

mockMvc.perform(createMessage)
		.andExpect(status().is3xxRedirection())
		.andExpect(redirectedUrl("/messages/123"));

This would reduce the risk of our test incorrectly passing, but there are still some problems.

  • What if we have multiple forms on our page? Admittedly we could update our xpath expressions, but they get more complicated the more factors we take into account (Are the fields the correct type? Are the fields enabled? etc.).
  • Another issue is that we are doing double the work we would expect. We must first verify the view, and then we submit the view with the same parameters we just verified. Ideally this could be done all at once.
  • Finally, there are some things that we still cannot account for. For example, what if the form has JavaScript validation that we wish to test as well?

The overall problem is that testing a web page does not involve a single interaction. Instead, it is a combination of how the user interacts with a web page and how that web page interacts with other resources. For example, the result of a form view is used as the input to a user for creating a message. In addition, our form view may potentially utilize additional resources which impact the behavior of the page, such as JavaScript validation.

Integration testing to the rescue?

To resolve the issues above we could perform end-to-end integration testing, but this has some obvious drawbacks. Consider testing the view that allows us to page through the messages. We might need the following tests.

  • Does our page display a notification to the user indicating that no results are available when the messages are empty?
  • Does our page properly display a single message?
  • Does our page properly support paging?

To set up these tests, we would need to ensure our database contained the proper messages in it. This leads to a number of additional challenges.

  • Ensuring the proper messages are in the database can be tedious; consider foreign key constraints.
  • Testing can become slow since each test would need to ensure that the database is in the correct state.
  • Since our database needs to be in a specific state, we cannot run tests in parallel.
  • Performing assertions on things like auto-generated ids, timestamps, etc. can be difficult.

These challenges do not mean that we should abandon end-to-end integration testing altogether. Instead, we can reduce the number of end-to-end integration tests by refactoring our detailed tests to use mock services which will execute much faster, more reliably, and without side effects. We can then implement a small number of true end-to-end integration tests that validate simple workflows to ensure that everything works together properly.

Enter HtmlUnit Integration

So how can we achieve a balance between testing the interactions of our pages and still retain good performance within our test suite? The answer is: "By integrating MockMvc with HtmlUnit."

HtmlUnit Integration Options

There are a number of ways to integrate MockMvc with HtmlUnit.

  • MockMvc and HtmlUnit: Use this option if you want to use the raw HtmlUnit libraries.
  • MockMvc and WebDriver: Use this option to ease development and reuse code between integration and end-to-end testing.
  • MockMvc and Geb: Use this option if you would like to use Groovy for testing, ease development, and reuse code between integration and end-to-end testing.

MockMvc and HtmlUnit

This section describes how to integrate MockMvc and HtmlUnit. Use this option if you want to use the raw HtmlUnit libraries.

MockMvc and HtmlUnit Setup

First, make sure that you have included a test dependency on net.sourceforge.htmlunit:htmlunit. In order to use HtmlUnit with Apache HttpComponents 4.5+, you will need to use HtmlUnit 2.18 or higher.

We can easily create an HtmlUnit WebClient that integrates with MockMvc using the MockMvcWebClientBuilder as follows.

@Autowired
WebApplicationContext context;

WebClient webClient;

@Before
public void setup() {
	webClient = MockMvcWebClientBuilder
		.webAppContextSetup(context)
		.build();
}
[Note]Note

This is a simple example of using MockMvcWebClientBuilder. For advanced usage see the section called “Advanced MockMvcWebClientBuilder”

This will ensure that any URL referencing localhost as the server will be directed to our MockMvc instance without the need for a real HTTP connection. Any other URL will be requested using a network connection as normal. This allows us to easily test the use of CDNs.

MockMvc and HtmlUnit Usage

Now we can use HtmlUnit as we normally would, but without the need to deploy our application to a Servlet container. For example, we can request the view to create a message with the following.

HtmlPage createMsgFormPage = webClient.getPage("http://localhost/messages/form");
[Note]Note

The default context path is "". Alternatively, we can specify the context path as illustrated in the section called “Advanced MockMvcWebClientBuilder”.

Once we have a reference to the HtmlPage, we can then fill out the form and submit it to create a message.

HtmlForm form = createMsgFormPage.getHtmlElementById("messageForm");
HtmlTextInput summaryInput = createMsgFormPage.getHtmlElementById("summary");
summaryInput.setValueAttribute("Spring Rocks");
HtmlTextArea textInput = createMsgFormPage.getHtmlElementById("text");
textInput.setText("In case you didn't know, Spring Rocks!");
HtmlSubmitInput submit = form.getOneHtmlElementByAttribute("input", "type", "submit");
HtmlPage newMessagePage = submit.click();

Finally, we can verify that a new message was created successfully. The following assertions use the AssertJ library.

assertThat(newMessagePage.getUrl().toString()).endsWith("/messages/123");
String id = newMessagePage.getHtmlElementById("id").getTextContent();
assertThat(id).isEqualTo("123");
String summary = newMessagePage.getHtmlElementById("summary").getTextContent();
assertThat(summary).isEqualTo("Spring Rocks");
String text = newMessagePage.getHtmlElementById("text").getTextContent();
assertThat(text).isEqualTo("In case you didn't know, Spring Rocks!");

This improves on our MockMvc test in a number of ways. First we no longer have to explicitly verify our form and then create a request that looks like the form. Instead, we request the form, fill it out, and submit it, thereby significantly reducing the overhead.

Another important factor is that HtmlUnit uses the Mozilla Rhino engine to evaluate JavaScript. This means that we can test the behavior of JavaScript within our pages as well!

Refer to the HtmlUnit documentation for additional information about using HtmlUnit.

Advanced MockMvcWebClientBuilder

In the examples so far, we have used MockMvcWebClientBuilder in the simplest way possible, by building a WebClient based on the WebApplicationContext loaded for us by the Spring TestContext Framework. This approach is repeated here.

@Autowired
WebApplicationContext context;

WebClient webClient;

@Before
public void setup() {
	webClient = MockMvcWebClientBuilder
		.webAppContextSetup(context)
		.build();
}

We can also specify additional configuration options.

WebClient webClient;

@Before
public void setup() {
	webClient = MockMvcWebClientBuilder
		// demonstrates applying a MockMvcConfigurer (Spring Security)
		.webAppContextSetup(context, springSecurity())
		// for illustration only - defaults to ""
		.contextPath("")
		// By default MockMvc is used for localhost only;
		// the following will use MockMvc for example.com and example.org as well
		.useMockMvcForHosts("example.com","example.org")
		.build();
}

As an alternative, we can perform the exact same setup by configuring the MockMvc instance separately and supplying it to the MockMvcWebClientBuilder as follows.

MockMvc mockMvc = MockMvcBuilders
		.webAppContextSetup(context)
		.apply(springSecurity())
		.build();

webClient = MockMvcWebClientBuilder
		.mockMvcSetup(mockMvc)
		// for illustration only - defaults to ""
		.contextPath("")
		// By default MockMvc is used for localhost only;
		// the following will use MockMvc for example.com and example.org as well
		.useMockMvcForHosts("example.com","example.org")
		.build();

This is more verbose, but by building the WebClient with a MockMvc instance we have the full power of MockMvc at our fingertips.

[Tip]Tip

For additional information on creating a MockMvc instance refer to the section called “Setup Options”.

MockMvc and WebDriver

In the previous sections, we have seen how to use MockMvc in conjunction with the raw HtmlUnit APIs. In this section, we will leverage additional abstractions within the Selenium WebDriver to make things even easier.

Why WebDriver and MockMvc?

We can already use HtmlUnit and MockMvc, so why would we want to use WebDriver? The Selenium WebDriver provides a very elegant API that allows us to easily organize our code. To better understand, let’s explore an example.

[Note]Note

Despite being a part of Selenium, WebDriver does not require a Selenium Server to run your tests.

Suppose we need to ensure that a message is created properly. The tests involve finding the HTML form input elements, filling them out, and making various assertions.

This approach results in numerous, separate tests because we want to test error conditions as well. For example, we want to ensure that we get an error if we fill out only part of the form. If we fill out the entire form, the newly created message should be displayed afterwards.

If one of the fields were named "summary", then we might have something like the following repeated in multiple places within our tests.

HtmlTextInput summaryInput = currentPage.getHtmlElementById("summary");
summaryInput.setValueAttribute(summary);

So what happens if we change the id to "smmry"? Doing so would force us to update all of our tests to incorporate this change! Of course, this violates the DRY Principle; so we should ideally extract this code into its own method as follows.

public HtmlPage createMessage(HtmlPage currentPage, String summary, String text) {
	setSummary(currentPage, summary);
	// ...
}

public void setSummary(HtmlPage currentPage, String summary) {
	HtmlTextInput summaryInput = currentPage.getHtmlElementById("summary");
	summaryInput.setValueAttribute(summary);
}

This ensures that we do not have to update all of our tests if we change the UI.

We might even take this a step further and place this logic within an Object that represents the HtmlPage we are currently on.

public class CreateMessagePage {

	final HtmlPage currentPage;

	final HtmlTextInput summaryInput;

	final HtmlSubmitInput submit;

	public CreateMessagePage(HtmlPage currentPage) {
		this.currentPage = currentPage;
		this.summaryInput = currentPage.getHtmlElementById("summary");
		this.submit = currentPage.getHtmlElementById("submit");
	}

	public <T> T createMessage(String summary, String text) throws Exception {
		setSummary(summary);

		HtmlPage result = submit.click();
		boolean error = CreateMessagePage.at(result);

		return (T) (error ? new CreateMessagePage(result) : new ViewMessagePage(result));
	}

	public void setSummary(String summary) throws Exception {
		summaryInput.setValueAttribute(summary);
	}

	public static boolean at(HtmlPage page) {
		return "Create Message".equals(page.getTitleText());
	}
}

Formerly, this pattern is known as the Page Object Pattern. While we can certainly do this with HtmlUnit, WebDriver provides some tools that we will explore in the following sections to make this pattern much easier to implement.

MockMvc and WebDriver Setup

To use Selenium WebDriver with the Spring MVC Test framework, make sure that your project includes a test dependency on org.seleniumhq.selenium:selenium-htmlunit-driver.

We can easily create a Selenium WebDriver that integrates with MockMvc using the MockMvcHtmlUnitDriverBuilder as follows.

@Autowired
WebApplicationContext context;

WebDriver driver;

@Before
public void setup() {
	driver = MockMvcHtmlUnitDriverBuilder
		.webAppContextSetup(context)
		.build();
}
[Note]Note

This is a simple example of using MockMvcHtmlUnitDriverBuilder. For more advanced usage, refer to the section called “Advanced MockMvcHtmlUnitDriverBuilder”

This will ensure that any URL referencing localhost as the server will be directed to our MockMvc instance without the need for a real HTTP connection. Any other URL will be requested using a network connection as normal. This allows us to easily test the use of CDNs.

MockMvc and WebDriver Usage

Now we can use WebDriver as we normally would, but without the need to deploy our application to a Servlet container. For example, we can request the view to create a message with the following.

CreateMessagePage page = CreateMessagePage.to(driver);

We can then fill out the form and submit it to create a message.

ViewMessagePage viewMessagePage =
	page.createMessage(ViewMessagePage.class, expectedSummary, expectedText);

This improves on the design of our HtmlUnit test by leveraging the Page Object Pattern. As we mentioned in the section called “Why WebDriver and MockMvc?”, we can use the Page Object Pattern with HtmlUnit, but it is much easier with WebDriver. Let’s take a look at our new CreateMessagePage implementation.

public class CreateMessagePage
		extends AbstractPage { 1

	2
	private WebElement summary;
	private WebElement text;

	3
	@FindBy(css = "input[type=submit]")
	private WebElement submit;

	public CreateMessagePage(WebDriver driver) {
		super(driver);
	}

	public <T> T createMessage(Class<T> resultPage, String summary, String details) {
		this.summary.sendKeys(summary);
		this.text.sendKeys(details);
		this.submit.click();
		return PageFactory.initElements(driver, resultPage);
	}

	public static CreateMessagePage to(WebDriver driver) {
		driver.get("http://localhost:9990/mail/messages/form");
		return PageFactory.initElements(driver, CreateMessagePage.class);
	}
}

1

The first thing you will notice is that CreateMessagePage extends the AbstractPage. We won’t go over the details of AbstractPage, but in summary it contains common functionality for all of our pages. For example, if our application has a navigational bar, global error messages, etc., this logic can be placed in a shared location.

2

The next thing you will notice is that we have a member variable for each of the parts of the HTML page that we are interested in. These are of type WebElement. WebDriver's PageFactory allows us to remove a lot of code from the HtmlUnit version of CreateMessagePage by automatically resolving each WebElement. The PageFactory#initElements(WebDriver,Class<T>) method will automatically resolve each WebElement by using the field name and looking it up by the id or name of the element within the HTML page.

3

We can use the @FindBy annotation to override the default lookup behavior. Our example demonstrates how to use the @FindBy annotation to look up our submit button using a css selector, input[type=submit].

Finally, we can verify that a new message was created successfully. The following assertions use the FEST assertion library.

assertThat(viewMessagePage.getMessage()).isEqualTo(expectedMessage);
assertThat(viewMessagePage.getSuccess()).isEqualTo("Successfully created a new message");

We can see that our ViewMessagePage allows us to interact with our custom domain model. For example, it exposes a method that returns a Message object.

public Message getMessage() throws ParseException {
	Message message = new Message();
	message.setId(getId());
	message.setCreated(getCreated());
	message.setSummary(getSummary());
	message.setText(getText());
	return message;
}

We can then leverage the rich domain objects in our assertions.

Lastly, don’t forget to close the WebDriver instance when the test is complete.

@After
public void destroy() {
	if (driver != null) {
		driver.close();
	}
}

For additional information on using WebDriver, refer to the Selenium WebDriver documentation.

Advanced MockMvcHtmlUnitDriverBuilder

In the examples so far, we have used MockMvcHtmlUnitDriverBuilder in the simplest way possible, by building a WebDriver based on the WebApplicationContext loaded for us by the Spring TestContext Framework. This approach is repeated here.

@Autowired
WebApplicationContext context;

WebDriver driver;

@Before
public void setup() {
	driver = MockMvcHtmlUnitDriverBuilder
		.webAppContextSetup(context)
		.build();
}

We can also specify additional configuration options.

WebDriver driver;

@Before
public void setup() {
	driver = MockMvcHtmlUnitDriverBuilder
		// demonstrates applying a MockMvcConfigurer (Spring Security)
		.webAppContextSetup(context, springSecurity())
		// for illustration only - defaults to ""
		.contextPath("")
		// By default MockMvc is used for localhost only;
		// the following will use MockMvc for example.com and example.org as well
		.useMockMvcForHosts("example.com","example.org")
		.build();
}

As an alternative, we can perform the exact same setup by configuring the MockMvc instance separately and supplying it to the MockMvcHtmlUnitDriverBuilder as follows.

MockMvc mockMvc = MockMvcBuilders
		.webAppContextSetup(context)
		.apply(springSecurity())
		.build();

driver = MockMvcHtmlUnitDriverBuilder
		.mockMvcSetup(mockMvc)
		// for illustration only - defaults to ""
		.contextPath("")
		// By default MockMvc is used for localhost only;
		// the following will use MockMvc for example.com and example.org as well
		.useMockMvcForHosts("example.com","example.org")
		.build();

This is more verbose, but by building the WebDriver with a MockMvc instance we have the full power of MockMvc at our fingertips.

[Tip]Tip

For additional information on creating a MockMvc instance refer to the section called “Setup Options”.

MockMvc and Geb

In the previous section, we saw how to use MockMvc with WebDriver. In this section, we will use Geb to make our tests even Groovy-er.

Why Geb and MockMvc?

Geb is backed by WebDriver, so it offers many of the same benefits that we get from WebDriver. However, Geb makes things even easier by taking care of some of the boilerplate code for us.

MockMvc and Geb Setup

We can easily initialize a Geb Browser with a Selenium WebDriver that uses MockMvc as follows.

def setup() {
	browser.driver = MockMvcHtmlUnitDriverBuilder
		.webAppContextSetup(context)
		.build()
}
[Note]Note

This is a simple example of using MockMvcHtmlUnitDriverBuilder. For more advanced usage, refer to the section called “Advanced MockMvcHtmlUnitDriverBuilder”

This will ensure that any URL referencing localhost as the server will be directed to our MockMvc instance without the need for a real HTTP connection. Any other URL will be requested using a network connection as normal. This allows us to easily test the use of CDNs.

MockMvc and Geb Usage

Now we can use Geb as we normally would, but without the need to deploy our application to a Servlet container. For example, we can request the view to create a message with the following:

to CreateMessagePage

We can then fill out the form and submit it to create a message.

when:
form.summary = expectedSummary
form.text = expectedMessage
submit.click(ViewMessagePage)

Any unrecognized method calls or property accesses/references that are not found will be forwarded to the current page object. This removes a lot of the boilerplate code we needed when using WebDriver directly.

As with direct WebDriver usage, this improves on the design of our HtmlUnit test by leveraging the Page Object Pattern. As mentioned previously, we can use the Page Object Pattern with HtmlUnit and WebDriver, but it is even easier with Geb. Let’s take a look at our new Groovy-based CreateMessagePage implementation.

class CreateMessagePage extends Page {
	static url = 'messages/form'
	static at = { assert title == 'Messages : Create'; true }
	static content =  {
		submit { $('input[type=submit]') }
		form { $('form') }
		errors(required:false) { $('label.error, .alert-error')?.text() }
	}
}

The first thing you will notice is that our CreateMessagePage extends Page. We won’t go over the details of Page, but in summary it contains common functionality for all of our pages. The next thing you will notice is that we define a URL in which this page can be found. This allows us to navigate to the page as follows.

to CreateMessagePage

We also have an at closure that determines if we are at the specified page. It should return true if we are on the correct page. This is why we can assert that we are on the correct page as follows.

then:
at CreateMessagePage
errors.contains('This field is required.')
[Note]Note

We use an assertion in the closure, so that we can determine where things went wrong if we were at the wrong page.

Next we create a content closure that specifies all the areas of interest within the page. We can use a jQuery-ish Navigator API to select the content we are interested in.

Finally, we can verify that a new message was created successfully.

then:
at ViewMessagePage
success == 'Successfully created a new message'
id
date
summary == expectedSummary
message == expectedMessage

For further details on how to get the most out of Geb, consult The Book of Geb user’s manual.

15.6.3 Client-Side REST Tests

Client-side tests can be used to test code that internally uses the RestTemplate. The idea is to declare expected requests and to provide "stub" responses so that you can focus on testing the code in isolation, i.e. without running a server. Here is an example:

RestTemplate restTemplate = new RestTemplate();

MockRestServiceServer mockServer = MockRestServiceServer.bindTo(restTemplate).build();
mockServer.expect(requestTo("/greeting")).andRespond(withSuccess());

// Test code that uses the above RestTemplate ...

mockServer.verify();

In the above example, MockRestServiceServer, the central class for client-side REST tests, configures the RestTemplate with a custom ClientHttpRequestFactory that asserts actual requests against expectations and returns "stub" responses. In this case we expect a request to "/greeting" and want to return a 200 response with "text/plain" content. We could define as additional expected requests and stub responses as needed. When expected requests and stub responses are defined, the RestTemplate can be used in client-side code as usual. At the end of testing mockServer.verify() can be used to verify that all expectations have been satisfied.

By default requests are expected in the order in which expectations were declared. You can set the ignoreExpectOrder option when building the server in which case all expectations are checked (in order) to find a match for a given request. That means requests are allowed to come in any order. Here is an example:

server = MockRestServiceServer.bindTo(restTemplate).ignoreExpectOrder(true).build();

Even with unordered requests by default each request is allowed to execute once only. The expect method provides an overloaded variant that accepts an ExpectedCount argument that specifies a count range, e.g. once, manyTimes, max, min, between, and so on. Here is an example:

RestTemplate restTemplate = new RestTemplate();

MockRestServiceServer mockServer = MockRestServiceServer.bindTo(restTemplate).build();
mockServer.expect(times(2), requestTo("/foo")).andRespond(withSuccess());
mockServer.expect(times(3), requestTo("/bar")).andRespond(withSuccess());

// ...

mockServer.verify();

Note that when ignoreExpectOrder is not set (the default), and therefore requests are expected in order of declaration, then that order only applies to the first of any expected request. For example if "/foo" is expected 2 times followed by "/bar" 3 times, then there should be a request to "/foo" before there is a request to "/bar" but aside from that subsequent "/foo" and "/bar" requests can come at any time.

As an alternative to all of the above the client-side test support also provides a ClientHttpRequestFactory implementation that can be configured into a RestTemplate to bind it to a MockMvc instance. That allows processing requests using actual server-side logic but without running a server. Here is an example:

MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
this.restTemplate = new RestTemplate(new MockMvcClientHttpRequestFactory(mockMvc));

// Test code that uses the above RestTemplate ...

mockServer.verify();

Static Imports

Just like with server-side tests, the fluent API for client-side tests requires a few static imports. Those are easy to find by searching "MockRest*". Eclipse users should add "MockRestRequestMatchers.*" and "MockRestResponseCreators.*" as "favorite static members" in the Eclipse preferences under Java → Editor → Content Assist → Favorites. That allows using content assist after typing the first character of the static method name. Other IDEs (e.g. IntelliJ) may not require any additional configuration. Just check the support for code completion on static members.

Further Examples of Client-side REST Tests

Spring MVC Test’s own tests include example tests of client-side REST tests.

15.7 PetClinic Example

The PetClinic application, available on GitHub, illustrates several features of the Spring TestContext Framework in a JUnit 4 environment. Most test functionality is included in the AbstractClinicTests, for which a partial listing is shown below:

import static org.junit.Assert.assertEquals;
// import ...

@ContextConfiguration
public abstract class AbstractClinicTests extends AbstractTransactionalJUnit4SpringContextTests {

    @Autowired
    protected Clinic clinic;

    @Test
    public void getVets() {
        Collection<Vet> vets = this.clinic.getVets();
        assertEquals("JDBC query must show the same number of vets",
            super.countRowsInTable("VETS"), vets.size());
        Vet v1 = EntityUtils.getById(vets, Vet.class, 2);
        assertEquals("Leary", v1.getLastName());
        assertEquals(1, v1.getNrOfSpecialties());
        assertEquals("radiology", (v1.getSpecialties().get(0)).getName());
        // ...
    }

    // ...
}

Notes:

  • This test case extends the AbstractTransactionalJUnit4SpringContextTests class, from which it inherits configuration for Dependency Injection (through the DependencyInjectionTestExecutionListener) and transactional behavior (through the TransactionalTestExecutionListener).
  • The clinic instance variable — the application object being tested — is set by Dependency Injection through @Autowired semantics.
  • The getVets() method illustrates how you can use the inherited countRowsInTable() method to easily verify the number of rows in a given table, thus verifying correct behavior of the application code being tested. This allows for stronger tests and lessens dependency on the exact test data. For example, you can add additional rows in the database without breaking tests.
  • Like many integration tests that use a database, most of the tests in AbstractClinicTests depend on a minimum amount of data already in the database before the test cases run. Alternatively, you might choose to populate the database within the test fixture set up of your test cases — again, within the same transaction as the tests.

The PetClinic application supports three data access technologies: JDBC, Hibernate, and JPA. By declaring @ContextConfiguration without any specific resource locations, the AbstractClinicTests class will have its application context loaded from the default location, AbstractClinicTests-context.xml, which declares a common DataSource. Subclasses specify additional context locations that must declare a PlatformTransactionManager and a concrete implementation of Clinic.

For example, the Hibernate implementation of the PetClinic tests contains the following implementation. For this example, HibernateClinicTests does not contain a single line of code: we only need to declare @ContextConfiguration, and the tests are inherited from AbstractClinicTests. Because @ContextConfiguration is declared without any specific resource locations, the Spring TestContext Framework loads an application context from all the beans defined in AbstractClinicTests-context.xml (i.e., the inherited locations) and HibernateClinicTests-context.xml, with HibernateClinicTests-context.xml possibly overriding beans defined in AbstractClinicTests-context.xml.

@ContextConfiguration
public class HibernateClinicTests extends AbstractClinicTests { }

In a large-scale application, the Spring configuration is often split across multiple files. Consequently, configuration locations are typically specified in a common base class for all application-specific integration tests. Such a base class may also add useful instance variables — populated by Dependency Injection, naturally — such as a SessionFactory in the case of an application using Hibernate.

As far as possible, you should have exactly the same Spring configuration files in your integration tests as in the deployed environment. One likely point of difference concerns database connection pooling and transaction infrastructure. If you are deploying to a full-blown application server, you will probably use its connection pool (available through JNDI) and JTA implementation. Thus in production you will use a JndiObjectFactoryBean or <jee:jndi-lookup> for the DataSource and JtaTransactionManager. JNDI and JTA will not be available in out-of-container integration tests, so you should use a combination like the Commons DBCP BasicDataSource and DataSourceTransactionManager or HibernateTransactionManager for them. You can factor out this variant behavior into a single XML file, having the choice between application server and a 'local' configuration separated from all other configuration, which will not vary between the test and production environments. In addition, it is advisable to use properties files for connection settings. See the PetClinic application for an example.