Testing Spring Boot Applications

A Spring Boot application is a Spring ApplicationContext, so nothing very special has to be done to test it beyond what you would normally do with a vanilla Spring context.

External properties, logging, and other features of Spring Boot are installed in the context by default only if you use SpringApplication to create it.

Spring Boot provides a @SpringBootTest annotation, which can be used as an alternative to the standard spring-test @ContextConfiguration annotation when you need Spring Boot features. The annotation works by creating the ApplicationContext used in your tests through SpringApplication. In addition to @SpringBootTest a number of other annotations are also provided for testing more specific slices of an application.

If you are using JUnit 4, do not forget to also add @RunWith(SpringRunner.class) to your test, otherwise the annotations will be ignored. If you are using JUnit 5, there is no need to add the equivalent @ExtendWith(SpringExtension.class) as @SpringBootTest and the other @…​Test annotations are already annotated with it.

By default, @SpringBootTest will not start a server. You can use the webEnvironment attribute of @SpringBootTest to further refine how your tests run:

  • MOCK(Default) : Loads a web ApplicationContext and provides a mock web environment. Embedded servers are not started when using this annotation. If a web environment is not available on your classpath, this mode transparently falls back to creating a regular non-web ApplicationContext. It can be used in conjunction with @AutoConfigureMockMvc or @AutoConfigureWebTestClient for mock-based testing of your web application.

  • RANDOM_PORT: Loads a WebServerApplicationContext and provides a real web environment. Embedded servers are started and listen on a random port.

  • DEFINED_PORT: Loads a WebServerApplicationContext and provides a real web environment. Embedded servers are started and listen on a defined port (from your application.properties) or on the default port of 8080.

  • NONE: Loads an ApplicationContext by using SpringApplication but does not provide any web environment (mock or otherwise).

If your test is @Transactional, it rolls back the transaction at the end of each test method by default. However, as using this arrangement with either RANDOM_PORT or DEFINED_PORT implicitly provides a real servlet environment, the HTTP client and server run in separate threads and, thus, in separate transactions. Any transaction initiated on the server does not roll back in this case.
@SpringBootTest with webEnvironment = WebEnvironment.RANDOM_PORT will also start the management server on a separate random port if your application uses a different port for the management server.

Detecting Web Application Type

If Spring MVC is available, a regular MVC-based application context is configured. If you have only Spring WebFlux, we will detect that and configure a WebFlux-based application context instead.

If both are present, Spring MVC takes precedence. If you want to test a reactive web application in this scenario, you must set the spring.main.web-application-type property:

import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest(properties = "spring.main.web-application-type=reactive")
class MyWebFluxTests {

	// ...

}

Detecting Test Configuration

If you are familiar with the Spring Test Framework, you may be used to using @ContextConfiguration(classes=…​) in order to specify which Spring @Configuration to load. Alternatively, you might have often used nested @Configuration classes within your test.

When testing Spring Boot applications, this is often not required. Spring Boot’s @*Test annotations search for your primary configuration automatically whenever you do not explicitly define one.

The search algorithm works up from the package that contains the test until it finds a class annotated with @SpringBootApplication or @SpringBootConfiguration. As long as you structured your code in a sensible way, your main configuration is usually found.

If you use a test annotation to test a more specific slice of your application, you should avoid adding configuration settings that are specific to a particular area on the main method’s application class.

The underlying component scan configuration of @SpringBootApplication defines exclude filters that are used to make sure slicing works as expected. If you are using an explicit @ComponentScan directive on your @SpringBootApplication-annotated class, be aware that those filters will be disabled. If you are using slicing, you should define them again.

If you want to customize the primary configuration, you can use a nested @TestConfiguration class. Unlike a nested @Configuration class, which would be used instead of your application’s primary configuration, a nested @TestConfiguration class is used in addition to your application’s primary configuration.

Spring’s test framework caches application contexts between tests. Therefore, as long as your tests share the same configuration (no matter how it is discovered), the potentially time-consuming process of loading the context happens only once.

Using the Test Configuration Main Method

Typically the test configuration discovered by @SpringBootTest will be your main @SpringBootApplication. In most well structured applications, this configuration class will also include the main method used to launch the application.

For example, the following is a very common code pattern for a typical Spring Boot application:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MyApplication {

	public static void main(String[] args) {
		SpringApplication.run(MyApplication.class, args);
	}

}

In the example above, the main method doesn’t do anything other than delegate to SpringApplication.run. It is, however, possible to have a more complex main method that applies customizations before calling SpringApplication.run.

For example, here is an application that changes the banner mode and sets additional profiles:

import org.springframework.boot.Banner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class MyApplication {

	public static void main(String[] args) {
		SpringApplication application = new SpringApplication(MyApplication.class);
		application.setBannerMode(Banner.Mode.OFF);
		application.setAdditionalProfiles("myprofile");
		application.run(args);
	}

}

Since customizations in the main method can affect the resulting ApplicationContext, it’s possible that you might also want to use the main method to create the ApplicationContext used in your tests. By default, @SpringBootTest will not call your main method, and instead the class itself is used directly to create the ApplicationContext

If you want to change this behavior, you can change the useMainMethod attribute of @SpringBootTest to UseMainMethod.ALWAYS or UseMainMethod.WHEN_AVAILABLE. When set to ALWAYS, the test will fail if no main method can be found. When set to WHEN_AVAILABLE the main method will be used if it is available, otherwise the standard loading mechanism will be used.

For example, the following test will invoke the main method of MyApplication in order to create the ApplicationContext. If the main method sets additional profiles then those will be active when the ApplicationContext starts.

import org.junit.jupiter.api.Test;

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.UseMainMethod;

@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
class MyApplicationTests {

	@Test
	void exampleTest() {
		// ...
	}

}

Excluding Test Configuration

If your application uses component scanning (for example, if you use @SpringBootApplication or @ComponentScan), you may find top-level configuration classes that you created only for specific tests accidentally get picked up everywhere.

As we have seen earlier, @TestConfiguration can be used on an inner class of a test to customize the primary configuration. @TestConfiguration can also be used on a top-level class. Doing so indicates that the class should not be picked up by scanning. You can then import the class explicitly where it is required, as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.Import;

@SpringBootTest
@Import(MyTestsConfiguration.class)
class MyTests {

	@Test
	void exampleTest() {
		// ...
	}

}
If you directly use @ComponentScan (that is, not through @SpringBootApplication) you need to register the TypeExcludeFilter with it. See the Javadoc for details.
An imported @TestConfiguration is processed earlier than an inner-class @TestConfiguration and an imported @TestConfiguration will be processed before any configuration found through component scanning. Generally speaking, this difference in ordering has no noticeable effect but it is something to be aware of if you’re relying on bean overriding.

Using Application Arguments

If your application expects arguments, you can have @SpringBootTest inject them using the args attribute.

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.test.context.SpringBootTest;

import static org.assertj.core.api.Assertions.assertThat;

@SpringBootTest(args = "--app.test=one")
class MyApplicationArgumentTests {

	@Test
	void applicationArgumentsPopulated(@Autowired ApplicationArguments args) {
		assertThat(args.getOptionNames()).containsOnly("app.test");
		assertThat(args.getOptionValues("app.test")).containsOnly("one");
	}

}

Testing With a Mock Environment

By default, @SpringBootTest does not start the server but instead sets up a mock environment for testing web endpoints.

With Spring MVC, we can query our web endpoints using MockMvc or WebTestClient, as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@SpringBootTest
@AutoConfigureMockMvc
class MyMockMvcTests {

	@Test
	void testWithMockMvc(@Autowired MockMvc mvc) throws Exception {
		mvc.perform(get("/")).andExpect(status().isOk()).andExpect(content().string("Hello World"));
	}

	// If Spring WebFlux is on the classpath, you can drive MVC tests with a WebTestClient
	@Test
	void testWithWebTestClient(@Autowired WebTestClient webClient) {
		webClient
				.get().uri("/")
				.exchange()
				.expectStatus().isOk()
				.expectBody(String.class).isEqualTo("Hello World");
	}

}
If you want to focus only on the web layer and not start a complete ApplicationContext, consider using @WebMvcTest instead.

With Spring WebFlux endpoints, you can use WebTestClient as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;

@SpringBootTest
@AutoConfigureWebTestClient
class MyMockWebTestClientTests {

	@Test
	void exampleTest(@Autowired WebTestClient webClient) {
		webClient
			.get().uri("/")
			.exchange()
			.expectStatus().isOk()
			.expectBody(String.class).isEqualTo("Hello World");
	}

}

Testing within a mocked environment is usually faster than running with a full servlet container. However, since mocking occurs at the Spring MVC layer, code that relies on lower-level servlet container behavior cannot be directly tested with MockMvc.

For example, Spring Boot’s error handling is based on the “error page” support provided by the servlet container. This means that, whilst you can test your MVC layer throws and handles exceptions as expected, you cannot directly test that a specific custom error page is rendered. If you need to test these lower-level concerns, you can start a fully running server as described in the next section.

Testing With a Running Server

If you need to start a full running server, we recommend that you use random ports. If you use @SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT), an available port is picked at random each time your test runs.

The @LocalServerPort annotation can be used to inject the actual port used into your test. For convenience, tests that need to make REST calls to the started server can additionally @Autowire a WebTestClient, which resolves relative links to the running server and comes with a dedicated API for verifying responses, as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.test.web.reactive.server.WebTestClient;

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortWebTestClientTests {

	@Test
	void exampleTest(@Autowired WebTestClient webClient) {
		webClient
			.get().uri("/")
			.exchange()
			.expectStatus().isOk()
			.expectBody(String.class).isEqualTo("Hello World");
	}

}
WebTestClient can also used with a mock environment, removing the need for a running server, by annotating your test class with @AutoConfigureWebTestClient.

This setup requires spring-webflux on the classpath. If you can not or will not add webflux, Spring Boot also provides a TestRestTemplate facility:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;

import static org.assertj.core.api.Assertions.assertThat;

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortTestRestTemplateTests {

	@Test
	void exampleTest(@Autowired TestRestTemplate restTemplate) {
		String body = restTemplate.getForObject("/", String.class);
		assertThat(body).isEqualTo("Hello World");
	}

}

Customizing WebTestClient

To customize the WebTestClient bean, configure a WebTestClientBuilderCustomizer bean. Any such beans are called with the WebTestClient.Builder that is used to create the WebTestClient.

Using JMX

As the test context framework caches context, JMX is disabled by default to prevent identical components to register on the same domain. If such test needs access to an MBeanServer, consider marking it dirty as well:

import javax.management.MBeanServer;

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.annotation.DirtiesContext;

import static org.assertj.core.api.Assertions.assertThat;

@SpringBootTest(properties = "spring.jmx.enabled=true")
@DirtiesContext
class MyJmxTests {

	@Autowired
	private MBeanServer mBeanServer;

	@Test
	void exampleTest() {
		assertThat(this.mBeanServer.getDomains()).contains("java.lang");
		// ...
	}

}

Using Observations

If you annotate a sliced test with @AutoConfigureObservability, it auto-configures an ObservationRegistry.

Using Metrics

Regardless of your classpath, meter registries, except the in-memory backed, are not auto-configured when using @SpringBootTest.

If you need to export metrics to a different backend as part of an integration test, annotate it with @AutoConfigureObservability.

If you annotate a sliced test with @AutoConfigureObservability, it auto-configures an in-memory MeterRegistry. Data exporting in sliced tests is not supported with the @AutoConfigureObservability annotation.

Using Tracing

Regardless of your classpath, tracing components which are reporting data are not auto-configured when using @SpringBootTest.

If you need those components as part of an integration test, annotate the test with @AutoConfigureObservability.

If you have created your own reporting components (e.g. a custom SpanExporter or SpanHandler) and you don’t want them to be active in tests, you can use the @ConditionalOnEnabledTracing annotation to disable them.

If you annotate a sliced test with @AutoConfigureObservability, it auto-configures a no-op Tracer. Data exporting in sliced tests is not supported with the @AutoConfigureObservability annotation.

Mocking and Spying Beans

When running tests, it is sometimes necessary to mock certain components within your application context. For example, you may have a facade over some remote service that is unavailable during development. Mocking can also be useful when you want to simulate failures that might be hard to trigger in a real environment.

Spring Boot includes a @MockBean annotation that can be used to define a Mockito mock for a bean inside your ApplicationContext. You can use the annotation to add new beans or replace a single existing bean definition. The annotation can be used directly on test classes, on fields within your test, or on @Configuration classes and fields. When used on a field, the instance of the created mock is also injected. Mock beans are automatically reset after each test method.

If your test uses one of Spring Boot’s test annotations (such as @SpringBootTest), this feature is automatically enabled. To use this feature with a different arrangement, listeners must be explicitly added, as shown in the following example:

import org.springframework.boot.test.mock.mockito.MockitoTestExecutionListener;
import org.springframework.boot.test.mock.mockito.ResetMocksTestExecutionListener;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestExecutionListeners;

@ContextConfiguration(classes = MyConfig.class)
@TestExecutionListeners({ MockitoTestExecutionListener.class, ResetMocksTestExecutionListener.class })
class MyTests {

	// ...

}

The following example replaces an existing RemoteService bean with a mock implementation:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.mock.mockito.MockBean;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.BDDMockito.given;

@SpringBootTest
class MyTests {

	@Autowired
	private Reverser reverser;

	@MockBean
	private RemoteService remoteService;

	@Test
	void exampleTest() {
		given(this.remoteService.getValue()).willReturn("spring");
		String reverse = this.reverser.getReverseValue(); // Calls injected RemoteService
		assertThat(reverse).isEqualTo("gnirps");
	}

}
@MockBean cannot be used to mock the behavior of a bean that is exercised during application context refresh. By the time the test is executed, the application context refresh has completed and it is too late to configure the mocked behavior. We recommend using a @Bean method to create and configure the mock in this situation.

Additionally, you can use @SpyBean to wrap any existing bean with a Mockito spy. See the Javadoc for full details.

While Spring’s test framework caches application contexts between tests and reuses a context for tests sharing the same configuration, the use of @MockBean or @SpyBean influences the cache key, which will most likely increase the number of contexts.
If you are using @SpyBean to spy on a bean with @Cacheable methods that refer to parameters by name, your application must be compiled with -parameters. This ensures that the parameter names are available to the caching infrastructure once the bean has been spied upon.
When you are using @SpyBean to spy on a bean that is proxied by Spring, you may need to remove Spring’s proxy in some situations, for example when setting expectations using given or when. Use AopTestUtils.getTargetObject(yourProxiedSpy) to do so.

Auto-configured Tests

Spring Boot’s auto-configuration system works well for applications but can sometimes be a little too much for tests. It often helps to load only the parts of the configuration that are required to test a “slice” of your application. For example, you might want to test that Spring MVC controllers are mapping URLs correctly, and you do not want to involve database calls in those tests, or you might want to test JPA entities, and you are not interested in the web layer when those tests run.

The spring-boot-test-autoconfigure module includes a number of annotations that can be used to automatically configure such “slices”. Each of them works in a similar way, providing a @…​Test annotation that loads the ApplicationContext and one or more @AutoConfigure…​ annotations that can be used to customize auto-configuration settings.

Each slice restricts component scan to appropriate components and loads a very restricted set of auto-configuration classes. If you need to exclude one of them, most @…​Test annotations provide an excludeAutoConfiguration attribute. Alternatively, you can use @ImportAutoConfiguration#exclude.
Including multiple “slices” by using several @…​Test annotations in one test is not supported. If you need multiple “slices”, pick one of the @…​Test annotations and include the @AutoConfigure…​ annotations of the other “slices” by hand.
It is also possible to use the @AutoConfigure…​ annotations with the standard @SpringBootTest annotation. You can use this combination if you are not interested in “slicing” your application but you want some of the auto-configured test beans.

Auto-configured JSON Tests

To test that object JSON serialization and deserialization is working as expected, you can use the @JsonTest annotation. @JsonTest auto-configures the available supported JSON mapper, which can be one of the following libraries:

  • Jackson ObjectMapper, any @JsonComponent beans and any Jackson Modules

  • Gson

  • Jsonb

A list of the auto-configurations that are enabled by @JsonTest can be found in the appendix.

If you need to configure elements of the auto-configuration, you can use the @AutoConfigureJsonTesters annotation.

Spring Boot includes AssertJ-based helpers that work with the JSONAssert and JsonPath libraries to check that JSON appears as expected. The JacksonTester, GsonTester, JsonbTester, and BasicJsonTester classes can be used for Jackson, Gson, Jsonb, and Strings respectively. Any helper fields on the test class can be @Autowired when using @JsonTest. The following example shows a test class for Jackson:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.json.JsonTest;
import org.springframework.boot.test.json.JacksonTester;

import static org.assertj.core.api.Assertions.assertThat;

@JsonTest
class MyJsonTests {

	@Autowired
	private JacksonTester<VehicleDetails> json;

	@Test
	void serialize() throws Exception {
		VehicleDetails details = new VehicleDetails("Honda", "Civic");
		// Assert against a `.json` file in the same package as the test
		assertThat(this.json.write(details)).isEqualToJson("expected.json");
		// Or use JSON path based assertions
		assertThat(this.json.write(details)).hasJsonPathStringValue("@.make");
		assertThat(this.json.write(details)).extractingJsonPathStringValue("@.make").isEqualTo("Honda");
	}

	@Test
	void deserialize() throws Exception {
		String content = "{\"make\":\"Ford\",\"model\":\"Focus\"}";
		assertThat(this.json.parse(content)).isEqualTo(new VehicleDetails("Ford", "Focus"));
		assertThat(this.json.parseObject(content).getMake()).isEqualTo("Ford");
	}

}
JSON helper classes can also be used directly in standard unit tests. To do so, call the initFields method of the helper in your @Before method if you do not use @JsonTest.

If you use Spring Boot’s AssertJ-based helpers to assert on a number value at a given JSON path, you might not be able to use isEqualTo depending on the type. Instead, you can use AssertJ’s satisfies to assert that the value matches the given condition. For instance, the following example asserts that the actual number is a float value close to 0.15 within an offset of 0.01.

	@Test
	void someTest() throws Exception {
		SomeObject value = new SomeObject(0.152f);
		assertThat(this.json.write(value)).extractingJsonPathNumberValue("@.test.numberValue")
			.satisfies((number) -> assertThat(number.floatValue()).isCloseTo(0.15f, within(0.01f)));
	}

Auto-configured Spring MVC Tests

To test whether Spring MVC controllers are working as expected, use the @WebMvcTest annotation. @WebMvcTest auto-configures the Spring MVC infrastructure and limits scanned beans to @Controller, @ControllerAdvice, @JsonComponent, Converter, GenericConverter, Filter, HandlerInterceptor, WebMvcConfigurer, WebMvcRegistrations, and HandlerMethodArgumentResolver. Regular @Component and @ConfigurationProperties beans are not scanned when the @WebMvcTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configuration settings that are enabled by @WebMvcTest can be found in the appendix.
If you need to register extra components, such as the Jackson Module, you can import additional configuration classes by using @Import on your test.

Often, @WebMvcTest is limited to a single controller and is used in combination with @MockBean to provide mock implementations for required collaborators.

@WebMvcTest also auto-configures MockMvc. Mock MVC offers a powerful way to quickly test MVC controllers without needing to start a full HTTP server.

You can also auto-configure MockMvc in a non-@WebMvcTest (such as @SpringBootTest) by annotating it with @AutoConfigureMockMvc. The following example uses MockMvc: 
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.docs.features.testing.springbootapplications.springmvctests.UserVehicleController;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import static org.mockito.BDDMockito.given;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@WebMvcTest(UserVehicleController.class)
class MyControllerTests {

	@Autowired
	private MockMvc mvc;

	@MockBean
	private UserVehicleService userVehicleService;

	@Test
	void testExample() throws Exception {
		given(this.userVehicleService.getVehicleDetails("sboot"))
			.willReturn(new VehicleDetails("Honda", "Civic"));
		this.mvc.perform(get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
			.andExpect(status().isOk())
			.andExpect(content().string("Honda Civic"));
	}

}
If you need to configure elements of the auto-configuration (for example, when servlet filters should be applied) you can use attributes in the @AutoConfigureMockMvc annotation.

If you use HtmlUnit and Selenium, auto-configuration also provides an HtmlUnit WebClient bean and/or a Selenium WebDriver bean. The following example uses HtmlUnit:

import com.gargoylesoftware.htmlunit.WebClient;
import com.gargoylesoftware.htmlunit.html.HtmlPage;
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.docs.features.testing.springbootapplications.springmvctests.UserVehicleController;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.BDDMockito.given;

@WebMvcTest(UserVehicleController.class)
class MyHtmlUnitTests {

	@Autowired
	private WebClient webClient;

	@MockBean
	private UserVehicleService userVehicleService;

	@Test
	void testExample() throws Exception {
		given(this.userVehicleService.getVehicleDetails("sboot")).willReturn(new VehicleDetails("Honda", "Civic"));
		HtmlPage page = this.webClient.getPage("/sboot/vehicle.html");
		assertThat(page.getBody().getTextContent()).isEqualTo("Honda Civic");
	}

}
By default, Spring Boot puts WebDriver beans in a special “scope” to ensure that the driver exits after each test and that a new instance is injected. If you do not want this behavior, you can add @Scope("singleton") to your WebDriver @Bean definition.
The webDriver scope created by Spring Boot will replace any user defined scope of the same name. If you define your own webDriver scope you may find it stops working when you use @WebMvcTest.

If you have Spring Security on the classpath, @WebMvcTest will also scan WebSecurityConfigurer beans. Instead of disabling security completely for such tests, you can use Spring Security’s test support. More details on how to use Spring Security’s MockMvc support can be found in this Testing With Spring Security how-to section.

Sometimes writing Spring MVC tests is not enough; Spring Boot can help you run full end-to-end tests with an actual server.

Auto-configured Spring WebFlux Tests

To test that Spring WebFlux controllers are working as expected, you can use the @WebFluxTest annotation. @WebFluxTest auto-configures the Spring WebFlux infrastructure and limits scanned beans to @Controller, @ControllerAdvice, @JsonComponent, Converter, GenericConverter, WebFilter, and WebFluxConfigurer. Regular @Component and @ConfigurationProperties beans are not scanned when the @WebFluxTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @WebFluxTest can be found in the appendix.
If you need to register extra components, such as Jackson Module, you can import additional configuration classes using @Import on your test.

Often, @WebFluxTest is limited to a single controller and used in combination with the @MockBean annotation to provide mock implementations for required collaborators.

@WebFluxTest also auto-configures WebTestClient, which offers a powerful way to quickly test WebFlux controllers without needing to start a full HTTP server.

You can also auto-configure WebTestClient in a non-@WebFluxTest (such as @SpringBootTest) by annotating it with @AutoConfigureWebTestClient. The following example shows a class that uses both @WebFluxTest and a WebTestClient: 
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.docs.features.testing.springbootapplications.springwebfluxtests.UserVehicleController;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.reactive.server.WebTestClient;

import static org.mockito.BDDMockito.given;

@WebFluxTest(UserVehicleController.class)
class MyControllerTests {

	@Autowired
	private WebTestClient webClient;

	@MockBean
	private UserVehicleService userVehicleService;

	@Test
	void testExample() {
		given(this.userVehicleService.getVehicleDetails("sboot"))
			.willReturn(new VehicleDetails("Honda", "Civic"));
		this.webClient.get().uri("/sboot/vehicle").accept(MediaType.TEXT_PLAIN).exchange()
			.expectStatus().isOk()
			.expectBody(String.class).isEqualTo("Honda Civic");
	}

}
This setup is only supported by WebFlux applications as using WebTestClient in a mocked web application only works with WebFlux at the moment.
@WebFluxTest cannot detect routes registered through the functional web framework. For testing RouterFunction beans in the context, consider importing your RouterFunction yourself by using @Import or by using @SpringBootTest.
@WebFluxTest cannot detect custom security configuration registered as a @Bean of type SecurityWebFilterChain. To include that in your test, you will need to import the configuration that registers the bean by using @Import or by using @SpringBootTest.
Sometimes writing Spring WebFlux tests is not enough; Spring Boot can help you run full end-to-end tests with an actual server.

Auto-configured Spring GraphQL Tests

Spring GraphQL offers a dedicated testing support module; you’ll need to add it to your project:

Maven
<dependencies>
	<dependency>
		<groupId>org.springframework.graphql</groupId>
		<artifactId>spring-graphql-test</artifactId>
		<scope>test</scope>
	</dependency>
	<!-- Unless already present in the compile scope -->
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-webflux</artifactId>
		<scope>test</scope>
	</dependency>
</dependencies>
Gradle
dependencies {
	testImplementation("org.springframework.graphql:spring-graphql-test")
	// Unless already present in the implementation configuration
	testImplementation("org.springframework.boot:spring-boot-starter-webflux")
}

This testing module ships the GraphQlTester. The tester is heavily used in test, so be sure to become familiar with using it. There are GraphQlTester variants and Spring Boot will auto-configure them depending on the type of tests:

  • the ExecutionGraphQlServiceTester performs tests on the server side, without a client nor a transport

  • the HttpGraphQlTester performs tests with a client that connects to a server, with or without a live server

Spring Boot helps you to test your Spring GraphQL Controllers with the @GraphQlTest annotation. @GraphQlTest auto-configures the Spring GraphQL infrastructure, without any transport nor server being involved. This limits scanned beans to @Controller, RuntimeWiringConfigurer, JsonComponent, Converter, GenericConverter, DataFetcherExceptionResolver, Instrumentation and GraphQlSourceBuilderCustomizer. Regular @Component and @ConfigurationProperties beans are not scanned when the @GraphQlTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @GraphQlTest can be found in the appendix.

Often, @GraphQlTest is limited to a set of controllers and used in combination with the @MockBean annotation to provide mock implementations for required collaborators.

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.docs.web.graphql.runtimewiring.GreetingController;
import org.springframework.boot.test.autoconfigure.graphql.GraphQlTest;
import org.springframework.graphql.test.tester.GraphQlTester;

@GraphQlTest(GreetingController.class)
class GreetingControllerTests {

	@Autowired
	private GraphQlTester graphQlTester;

	@Test
	void shouldGreetWithSpecificName() {
		this.graphQlTester.document("{ greeting(name: \"Alice\") } ")
			.execute()
			.path("greeting")
			.entity(String.class)
			.isEqualTo("Hello, Alice!");
	}

	@Test
	void shouldGreetWithDefaultName() {
		this.graphQlTester.document("{ greeting } ")
			.execute()
			.path("greeting")
			.entity(String.class)
			.isEqualTo("Hello, Spring!");
	}

}

@SpringBootTest tests are full integration tests and involve the entire application. When using a random or defined port, a live server is configured and an HttpGraphQlTester bean is contributed automatically so you can use it to test your server. When a MOCK environment is configured, you can also request an HttpGraphQlTester bean by annotating your test class with @AutoConfigureHttpGraphQlTester:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.graphql.tester.AutoConfigureHttpGraphQlTester;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.graphql.test.tester.HttpGraphQlTester;

@AutoConfigureHttpGraphQlTester
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.MOCK)
class GraphQlIntegrationTests {

	@Test
	void shouldGreetWithSpecificName(@Autowired HttpGraphQlTester graphQlTester) {
		HttpGraphQlTester authenticatedTester = graphQlTester.mutate()
			.webTestClient((client) -> client.defaultHeaders((headers) -> headers.setBasicAuth("admin", "ilovespring")))
			.build();
		authenticatedTester.document("{ greeting(name: \"Alice\") } ")
			.execute()
			.path("greeting")
			.entity(String.class)
			.isEqualTo("Hello, Alice!");
	}

}

Auto-configured Data Cassandra Tests

You can use @DataCassandraTest to test Cassandra applications. By default, it configures a CassandraTemplate, scans for @Table classes, and configures Spring Data Cassandra repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataCassandraTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using Cassandra with Spring Boot, see "Cassandra".)

A list of the auto-configuration settings that are enabled by @DataCassandraTest can be found in the appendix.

The following example shows a typical setup for using Cassandra tests in Spring Boot:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.cassandra.DataCassandraTest;

@DataCassandraTest
class MyDataCassandraTests {

	@Autowired
	private SomeRepository repository;

}

Auto-configured Data Couchbase Tests

You can use @DataCouchbaseTest to test Couchbase applications. By default, it configures a CouchbaseTemplate or ReactiveCouchbaseTemplate, scans for @Document classes, and configures Spring Data Couchbase repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataCouchbaseTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using Couchbase with Spring Boot, see "Couchbase", earlier in this chapter.)

A list of the auto-configuration settings that are enabled by @DataCouchbaseTest can be found in the appendix.

The following example shows a typical setup for using Couchbase tests in Spring Boot:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.couchbase.DataCouchbaseTest;

@DataCouchbaseTest
class MyDataCouchbaseTests {

	@Autowired
	private SomeRepository repository;

	// ...

}

Auto-configured Data Elasticsearch Tests

You can use @DataElasticsearchTest to test Elasticsearch applications. By default, it configures an ElasticsearchRestTemplate, scans for @Document classes, and configures Spring Data Elasticsearch repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataElasticsearchTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using Elasticsearch with Spring Boot, see "Elasticsearch", earlier in this chapter.)

A list of the auto-configuration settings that are enabled by @DataElasticsearchTest can be found in the appendix.

The following example shows a typical setup for using Elasticsearch tests in Spring Boot:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.elasticsearch.DataElasticsearchTest;

@DataElasticsearchTest
class MyDataElasticsearchTests {

	@Autowired
	private SomeRepository repository;

	// ...

}

Auto-configured Data JPA Tests

You can use the @DataJpaTest annotation to test JPA applications. By default, it scans for @Entity classes and configures Spring Data JPA repositories. If an embedded database is available on the classpath, it configures one as well. SQL queries are logged by default by setting the spring.jpa.show-sql property to true. This can be disabled using the showSql attribute of the annotation.

Regular @Component and @ConfigurationProperties beans are not scanned when the @DataJpaTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configuration settings that are enabled by @DataJpaTest can be found in the appendix.

By default, data JPA tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class as follows:

import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

@DataJpaTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyNonTransactionalTests {

	// ...

}

Data JPA tests may also inject a TestEntityManager bean, which provides an alternative to the standard JPA EntityManager that is specifically designed for tests.

TestEntityManager can also be auto-configured to any of your Spring-based test class by adding @AutoConfigureTestEntityManager. When doing so, make sure that your test is running in a transaction, for instance by adding @Transactional on your test class or method.

A JdbcTemplate is also available if you need that. The following example shows the @DataJpaTest annotation in use:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;

import static org.assertj.core.api.Assertions.assertThat;

@DataJpaTest
class MyRepositoryTests {

	@Autowired
	private TestEntityManager entityManager;

	@Autowired
	private UserRepository repository;

	@Test
	void testExample() {
		this.entityManager.persist(new User("sboot", "1234"));
		User user = this.repository.findByUsername("sboot");
		assertThat(user.getUsername()).isEqualTo("sboot");
		assertThat(user.getEmployeeNumber()).isEqualTo("1234");
	}

}

In-memory embedded databases generally work well for tests, since they are fast and do not require any installation. If, however, you prefer to run tests against a real database you can use the @AutoConfigureTestDatabase annotation, as shown in the following example:

import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase.Replace;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;

@DataJpaTest
@AutoConfigureTestDatabase(replace = Replace.NONE)
class MyRepositoryTests {

	// ...

}

Auto-configured JDBC Tests

@JdbcTest is similar to @DataJpaTest but is for tests that only require a DataSource and do not use Spring Data JDBC. By default, it configures an in-memory embedded database and a JdbcTemplate. Regular @Component and @ConfigurationProperties beans are not scanned when the @JdbcTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @JdbcTest can be found in the appendix.

By default, JDBC tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class, as follows:

import org.springframework.boot.test.autoconfigure.jdbc.JdbcTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

@JdbcTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyTransactionalTests {

}

If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase annotation in the same way as for @DataJpaTest. (See "Auto-configured Data JPA Tests".)

Auto-configured Data JDBC Tests

@DataJdbcTest is similar to @JdbcTest but is for tests that use Spring Data JDBC repositories. By default, it configures an in-memory embedded database, a JdbcTemplate, and Spring Data JDBC repositories. Only AbstractJdbcConfiguration subclasses are scanned when the @DataJdbcTest annotation is used, regular @Component and @ConfigurationProperties beans are not scanned. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @DataJdbcTest can be found in the appendix.

By default, Data JDBC tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole test class as shown in the JDBC example.

If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase annotation in the same way as for @DataJpaTest. (See "Auto-configured Data JPA Tests".)

Auto-configured Data R2DBC Tests

@DataR2dbcTest is similar to @DataJdbcTest but is for tests that use Spring Data R2DBC repositories. By default, it configures an in-memory embedded database, an R2dbcEntityTemplate, and Spring Data R2DBC repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataR2dbcTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @DataR2dbcTest can be found in the appendix.

By default, Data R2DBC tests are not transactional.

If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase annotation in the same way as for @DataJpaTest. (See "Auto-configured Data JPA Tests".)

Auto-configured jOOQ Tests

You can use @JooqTest in a similar fashion as @JdbcTest but for jOOQ-related tests. As jOOQ relies heavily on a Java-based schema that corresponds with the database schema, the existing DataSource is used. If you want to replace it with an in-memory database, you can use @AutoConfigureTestDatabase to override those settings. (For more about using jOOQ with Spring Boot, see "Using jOOQ".) Regular @Component and @ConfigurationProperties beans are not scanned when the @JooqTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configurations that are enabled by @JooqTest can be found in the appendix.

@JooqTest configures a DSLContext. The following example shows the @JooqTest annotation in use:

import org.jooq.DSLContext;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.jooq.JooqTest;

@JooqTest
class MyJooqTests {

	@Autowired
	private DSLContext dslContext;

	// ...

}

JOOQ tests are transactional and roll back at the end of each test by default. If that is not what you want, you can disable transaction management for a test or for the whole test class as shown in the JDBC example.

Auto-configured Data MongoDB Tests

You can use @DataMongoTest to test MongoDB applications. By default, it configures a MongoTemplate, scans for @Document classes, and configures Spring Data MongoDB repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataMongoTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using MongoDB with Spring Boot, see "MongoDB".)

A list of the auto-configuration settings that are enabled by @DataMongoTest can be found in the appendix.

The following class shows the @DataMongoTest annotation in use:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
import org.springframework.data.mongodb.core.MongoTemplate;

@DataMongoTest
class MyDataMongoDbTests {

	@Autowired
	private MongoTemplate mongoTemplate;

	// ...

}

Auto-configured Data Neo4j Tests

You can use @DataNeo4jTest to test Neo4j applications. By default, it scans for @Node classes, and configures Spring Data Neo4j repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataNeo4jTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using Neo4J with Spring Boot, see "Neo4j".)

A list of the auto-configuration settings that are enabled by @DataNeo4jTest can be found in the appendix.

The following example shows a typical setup for using Neo4J tests in Spring Boot:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.neo4j.DataNeo4jTest;

@DataNeo4jTest
class MyDataNeo4jTests {

	@Autowired
	private SomeRepository repository;

	// ...

}

By default, Data Neo4j tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class, as follows:

import org.springframework.boot.test.autoconfigure.data.neo4j.DataNeo4jTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

@DataNeo4jTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyDataNeo4jTests {

}
Transactional tests are not supported with reactive access. If you are using this style, you must configure @DataNeo4jTest tests as described above.

Auto-configured Data Redis Tests

You can use @DataRedisTest to test Redis applications. By default, it scans for @RedisHash classes and configures Spring Data Redis repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataRedisTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using Redis with Spring Boot, see "Redis".)

A list of the auto-configuration settings that are enabled by @DataRedisTest can be found in the appendix.

The following example shows the @DataRedisTest annotation in use:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.redis.DataRedisTest;

@DataRedisTest
class MyDataRedisTests {

	@Autowired
	private SomeRepository repository;

	// ...

}

Auto-configured Data LDAP Tests

You can use @DataLdapTest to test LDAP applications. By default, it configures an in-memory embedded LDAP (if available), configures an LdapTemplate, scans for @Entry classes, and configures Spring Data LDAP repositories. Regular @Component and @ConfigurationProperties beans are not scanned when the @DataLdapTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans. (For more about using LDAP with Spring Boot, see "LDAP".)

A list of the auto-configuration settings that are enabled by @DataLdapTest can be found in the appendix.

The following example shows the @DataLdapTest annotation in use:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.ldap.DataLdapTest;
import org.springframework.ldap.core.LdapTemplate;

@DataLdapTest
class MyDataLdapTests {

	@Autowired
	private LdapTemplate ldapTemplate;

	// ...

}

In-memory embedded LDAP generally works well for tests, since it is fast and does not require any developer installation. If, however, you prefer to run tests against a real LDAP server, you should exclude the embedded LDAP auto-configuration, as shown in the following example:

import org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration;
import org.springframework.boot.test.autoconfigure.data.ldap.DataLdapTest;

@DataLdapTest(excludeAutoConfiguration = EmbeddedLdapAutoConfiguration.class)
class MyDataLdapTests {

	// ...

}

Auto-configured REST Clients

You can use the @RestClientTest annotation to test REST clients. By default, it auto-configures Jackson, GSON, and Jsonb support, configures a RestTemplateBuilder and a RestClient.Builder, and adds support for MockRestServiceServer. Regular @Component and @ConfigurationProperties beans are not scanned when the @RestClientTest annotation is used. @EnableConfigurationProperties can be used to include @ConfigurationProperties beans.

A list of the auto-configuration settings that are enabled by @RestClientTest can be found in the appendix.

The specific beans that you want to test should be specified by using the value or components attribute of @RestClientTest.

When using a RestTemplateBuilder in the beans under test and RestTemplateBuilder.rootUri(String rootUri) has been called when building the RestTemplate, then the root URI should be omitted from the MockRestServiceServer expectations as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.client.RestClientTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.client.MockRestServiceServer;

import static org.assertj.core.api.Assertions.assertThat;
import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
import static org.springframework.test.web.client.response.MockRestResponseCreators.withSuccess;

@RestClientTest(org.springframework.boot.docs.testing.springbootapplications.autoconfiguredrestclient.RemoteVehicleDetailsService.class)
class MyRestTemplateServiceTests {

	@Autowired
	private RemoteVehicleDetailsService service;

	@Autowired
	private MockRestServiceServer server;

	@Test
	void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails() {
		this.server.expect(requestTo("/greet/details")).andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
		String greeting = this.service.callRestService();
		assertThat(greeting).isEqualTo("hello");
	}

}

When using a RestClient.Builder in the beans under test, or when using a RestTemplateBuilder without calling rootUri(String rootURI), the full URI must be used in the MockRestServiceServer expectations as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.client.RestClientTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.client.MockRestServiceServer;

import static org.assertj.core.api.Assertions.assertThat;
import static org.springframework.test.web.client.match.MockRestRequestMatchers.requestTo;
import static org.springframework.test.web.client.response.MockRestResponseCreators.withSuccess;

@RestClientTest(RemoteVehicleDetailsService.class)
class MyRestClientServiceTests {

	@Autowired
	private RemoteVehicleDetailsService service;

	@Autowired
	private MockRestServiceServer server;

	@Test
	void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails() {
		this.server.expect(requestTo("https://example.com/greet/details"))
			.andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
		String greeting = this.service.callRestService();
		assertThat(greeting).isEqualTo("hello");
	}

}

Auto-configured Spring REST Docs Tests

You can use the @AutoConfigureRestDocs annotation to use Spring REST Docs in your tests with Mock MVC, REST Assured, or WebTestClient. It removes the need for the JUnit extension in Spring REST Docs.

@AutoConfigureRestDocs can be used to override the default output directory (target/generated-snippets if you are using Maven or build/generated-snippets if you are using Gradle). It can also be used to configure the host, scheme, and port that appears in any documented URIs.

Auto-configured Spring REST Docs Tests With Mock MVC

@AutoConfigureRestDocs customizes the MockMvc bean to use Spring REST Docs when testing servlet-based web applications. You can inject it by using @Autowired and use it in your tests as you normally would when using Mock MVC and Spring REST Docs, as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@WebMvcTest(UserController.class)
@AutoConfigureRestDocs
class MyUserDocumentationTests {

	@Autowired
	private MockMvc mvc;

	@Test
	void listUsers() throws Exception {
		this.mvc.perform(get("/users").accept(MediaType.TEXT_PLAIN))
			.andExpect(status().isOk())
			.andDo(document("list-users"));
	}

}

If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs, you can use a RestDocsMockMvcConfigurationCustomizer bean, as shown in the following example:

import org.springframework.boot.test.autoconfigure.restdocs.RestDocsMockMvcConfigurationCustomizer;
import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.restdocs.mockmvc.MockMvcRestDocumentationConfigurer;
import org.springframework.restdocs.templates.TemplateFormats;

@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsMockMvcConfigurationCustomizer {

	@Override
	public void customize(MockMvcRestDocumentationConfigurer configurer) {
		configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
	}

}

If you want to make use of Spring REST Docs support for a parameterized output directory, you can create a RestDocumentationResultHandler bean. The auto-configuration calls alwaysDo with this result handler, thereby causing each MockMvc call to automatically generate the default snippets. The following example shows a RestDocumentationResultHandler being defined:

import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.restdocs.mockmvc.MockMvcRestDocumentation;
import org.springframework.restdocs.mockmvc.RestDocumentationResultHandler;

@TestConfiguration(proxyBeanMethods = false)
public class MyResultHandlerConfiguration {

	@Bean
	public RestDocumentationResultHandler restDocumentation() {
		return MockMvcRestDocumentation.document("{method-name}");
	}

}

Auto-configured Spring REST Docs Tests With WebTestClient

@AutoConfigureRestDocs can also be used with WebTestClient when testing reactive web applications. You can inject it by using @Autowired and use it in your tests as you normally would when using @WebFluxTest and Spring REST Docs, as shown in the following example:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.test.web.reactive.server.WebTestClient;

import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;

@WebFluxTest
@AutoConfigureRestDocs
class MyUsersDocumentationTests {

	@Autowired
	private WebTestClient webTestClient;

	@Test
	void listUsers() {
		this.webTestClient
			.get().uri("/")
		.exchange()
		.expectStatus()
			.isOk()
		.expectBody()
			.consumeWith(document("list-users"));
	}

}

If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs, you can use a RestDocsWebTestClientConfigurationCustomizer bean, as shown in the following example:

import org.springframework.boot.test.autoconfigure.restdocs.RestDocsWebTestClientConfigurationCustomizer;
import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.restdocs.webtestclient.WebTestClientRestDocumentationConfigurer;

@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsWebTestClientConfigurationCustomizer {

	@Override
	public void customize(WebTestClientRestDocumentationConfigurer configurer) {
		configurer.snippets().withEncoding("UTF-8");
	}

}

If you want to make use of Spring REST Docs support for a parameterized output directory, you can use a WebTestClientBuilderCustomizer to configure a consumer for every entity exchange result. The following example shows such a WebTestClientBuilderCustomizer being defined:

import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.boot.test.web.reactive.server.WebTestClientBuilderCustomizer;
import org.springframework.context.annotation.Bean;

import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;

@TestConfiguration(proxyBeanMethods = false)
public class MyWebTestClientBuilderCustomizerConfiguration {

	@Bean
	public WebTestClientBuilderCustomizer restDocumentation() {
		return (builder) -> builder.entityExchangeResultConsumer(document("{method-name}"));
	}

}

Auto-configured Spring REST Docs Tests With REST Assured

@AutoConfigureRestDocs makes a RequestSpecification bean, preconfigured to use Spring REST Docs, available to your tests. You can inject it by using @Autowired and use it in your tests as you normally would when using REST Assured and Spring REST Docs, as shown in the following example:

import io.restassured.specification.RequestSpecification;
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.server.LocalServerPort;

import static io.restassured.RestAssured.given;
import static org.hamcrest.Matchers.is;
import static org.springframework.restdocs.restassured.RestAssuredRestDocumentation.document;

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureRestDocs
class MyUserDocumentationTests {

	@Test
	void listUsers(@Autowired RequestSpecification documentationSpec, @LocalServerPort int port) {
		given(documentationSpec)
			.filter(document("list-users"))
		.when()
			.port(port)
			.get("/")
		.then().assertThat()
			.statusCode(is(200));
	}

}

If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs, a RestDocsRestAssuredConfigurationCustomizer bean can be used, as shown in the following example:

import org.springframework.boot.test.autoconfigure.restdocs.RestDocsRestAssuredConfigurationCustomizer;
import org.springframework.boot.test.context.TestConfiguration;
import org.springframework.restdocs.restassured.RestAssuredRestDocumentationConfigurer;
import org.springframework.restdocs.templates.TemplateFormats;

@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsRestAssuredConfigurationCustomizer {

	@Override
	public void customize(RestAssuredRestDocumentationConfigurer configurer) {
		configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
	}

}

Auto-configured Spring Web Services Tests

Auto-configured Spring Web Services Client Tests

You can use @WebServiceClientTest to test applications that call web services using the Spring Web Services project. By default, it configures a mock WebServiceServer bean and automatically customizes your WebServiceTemplateBuilder. (For more about using Web Services with Spring Boot, see "Web Services".)

A list of the auto-configuration settings that are enabled by @WebServiceClientTest can be found in the appendix.

The following example shows the @WebServiceClientTest annotation in use:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.webservices.client.WebServiceClientTest;
import org.springframework.ws.test.client.MockWebServiceServer;
import org.springframework.xml.transform.StringSource;

import static org.assertj.core.api.Assertions.assertThat;
import static org.springframework.ws.test.client.RequestMatchers.payload;
import static org.springframework.ws.test.client.ResponseCreators.withPayload;

@WebServiceClientTest(SomeWebService.class)
class MyWebServiceClientTests {

	@Autowired
	private MockWebServiceServer server;

	@Autowired
	private SomeWebService someWebService;

	@Test
	void mockServerCall() {
		this.server
			.expect(payload(new StringSource("<request/>")))
			.andRespond(withPayload(new StringSource("<response><status>200</status></response>")));
		assertThat(this.someWebService.test())
			.extracting(Response::getStatus)
			.isEqualTo(200);
	}

}

Auto-configured Spring Web Services Server Tests

You can use @WebServiceServerTest to test applications that implement web services using the Spring Web Services project. By default, it configures a MockWebServiceClient bean that can be used to call your web service endpoints. (For more about using Web Services with Spring Boot, see "Web Services".)

A list of the auto-configuration settings that are enabled by @WebServiceServerTest can be found in the appendix.

The following example shows the @WebServiceServerTest annotation in use:

import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.docs.features.testing.springbootapplications.autoconfiguredwebservices.server.ExampleEndpoint;
import org.springframework.boot.test.autoconfigure.webservices.server.WebServiceServerTest;
import org.springframework.ws.test.server.MockWebServiceClient;
import org.springframework.ws.test.server.RequestCreators;
import org.springframework.ws.test.server.ResponseMatchers;
import org.springframework.xml.transform.StringSource;

@WebServiceServerTest(ExampleEndpoint.class)
class MyWebServiceServerTests {

	@Autowired
	private MockWebServiceClient client;

	@Test
	void mockServerCall() {
		this.client
			.sendRequest(RequestCreators.withPayload(new StringSource("<ExampleRequest/>")))
			.andExpect(ResponseMatchers.payload(new StringSource("<ExampleResponse>42</ExampleResponse>")));
	}

}

Additional Auto-configuration and Slicing

Each slice provides one or more @AutoConfigure…​ annotations that namely defines the auto-configurations that should be included as part of a slice. Additional auto-configurations can be added on a test-by-test basis by creating a custom @AutoConfigure…​ annotation or by adding @ImportAutoConfiguration to the test as shown in the following example:

import org.springframework.boot.autoconfigure.ImportAutoConfiguration;
import org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration;
import org.springframework.boot.test.autoconfigure.jdbc.JdbcTest;

@JdbcTest
@ImportAutoConfiguration(IntegrationAutoConfiguration.class)
class MyJdbcTests {

}
Make sure to not use the regular @Import annotation to import auto-configurations as they are handled in a specific way by Spring Boot.

Alternatively, additional auto-configurations can be added for any use of a slice annotation by registering them in a file stored in META-INF/spring as shown in the following example:

META-INF/spring/org.springframework.boot.test.autoconfigure.jdbc.JdbcTest.imports
com.example.IntegrationAutoConfiguration

In this example, the com.example.IntegrationAutoConfiguration is enabled on every test annotated with @JdbcTest.

You can use comments with # in this file.
A slice or @AutoConfigure…​ annotation can be customized this way as long as it is meta-annotated with @ImportAutoConfiguration.

User Configuration and Slicing

If you structure your code in a sensible way, your @SpringBootApplication class is used by default as the configuration of your tests.

It then becomes important not to litter the application’s main class with configuration settings that are specific to a particular area of its functionality.

Assume that you are using Spring Data MongoDB, you rely on the auto-configuration for it, and you have enabled auditing. You could define your @SpringBootApplication as follows:

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.mongodb.config.EnableMongoAuditing;

@SpringBootApplication
@EnableMongoAuditing
public class MyApplication {

	// ...

}

Because this class is the source configuration for the test, any slice test actually tries to enable Mongo auditing, which is definitely not what you want to do. A recommended approach is to move that area-specific configuration to a separate @Configuration class at the same level as your application, as shown in the following example:

import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.config.EnableMongoAuditing;

@Configuration(proxyBeanMethods = false)
@EnableMongoAuditing
public class MyMongoConfiguration {

	// ...

}
Depending on the complexity of your application, you may either have a single @Configuration class for your customizations or one class per domain area. The latter approach lets you enable it in one of your tests, if necessary, with the @Import annotation. See this how-to section for more details on when you might want to enable specific @Configuration classes for slice tests.

Test slices exclude @Configuration classes from scanning. For example, for a @WebMvcTest, the following configuration will not include the given WebMvcConfigurer bean in the application context loaded by the test slice:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration(proxyBeanMethods = false)
public class MyWebConfiguration {

	@Bean
	public WebMvcConfigurer testConfigurer() {
		return new WebMvcConfigurer() {
			// ...
		};
	}

}

The configuration below will, however, cause the custom WebMvcConfigurer to be loaded by the test slice.

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Component
public class MyWebMvcConfigurer implements WebMvcConfigurer {

	// ...

}

Another source of confusion is classpath scanning. Assume that, while you structured your code in a sensible way, you need to scan an additional package. Your application may resemble the following code:

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan({ "com.example.app", "com.example.another" })
public class MyApplication {

	// ...

}

Doing so effectively overrides the default component scan directive with the side effect of scanning those two packages regardless of the slice that you chose. For instance, a @DataJpaTest seems to suddenly scan components and user configurations of your application. Again, moving the custom directive to a separate class is a good way to fix this issue.

If this is not an option for you, you can create a @SpringBootConfiguration somewhere in the hierarchy of your test so that it is used instead. Alternatively, you can specify a source for your test, which disables the behavior of finding a default one.

Using Spock to Test Spring Boot Applications

Spock 2.2 or later can be used to test a Spring Boot application. To do so, add a dependency on a -groovy-4.0 version of Spock’s spock-spring module to your application’s build. spock-spring integrates Spring’s test framework into Spock. See the documentation for Spock’s Spring module for further details.