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TestExecutionListener
Configuration
Spring provides the following TestExecutionListener
implementations that are registered
by default, exactly in the following order:
-
ServletTestExecutionListener
: Configures Servlet API mocks for aWebApplicationContext
. -
DirtiesContextBeforeModesTestExecutionListener
: Handles the@DirtiesContext
annotation for “before” modes. -
ApplicationEventsTestExecutionListener
: Provides support forApplicationEvents
. -
DependencyInjectionTestExecutionListener
: Provides dependency injection for the test instance. -
MicrometerObservationRegistryTestExecutionListener
: Provides support for Micrometer’sObservationRegistry
. -
DirtiesContextTestExecutionListener
: Handles the@DirtiesContext
annotation for “after” modes. -
TransactionalTestExecutionListener
: Provides transactional test execution with default rollback semantics. -
SqlScriptsTestExecutionListener
: Runs SQL scripts configured by using the@Sql
annotation. -
EventPublishingTestExecutionListener
: Publishes test execution events to the test’sApplicationContext
(see Test Execution Events).
Registering TestExecutionListener
Implementations
You can register TestExecutionListener
implementations explicitly for a test class, its
subclasses, and its nested classes by using the @TestExecutionListeners
annotation. See
annotation support and the javadoc for
@TestExecutionListeners
for details and examples.
Switching to default
TestExecutionListener implementationsIf you extend a class that is annotated with
|
Automatic Discovery of Default TestExecutionListener
Implementations
Registering TestExecutionListener
implementations by using @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 an entire test suite. This
issue is addressed through support for automatic discovery of default
TestExecutionListener
implementations through the SpringFactoriesLoader
mechanism.
Specifically, the spring-test
module declares all core default TestExecutionListener
implementations 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 TestExecutionListener
implementations to the list of default
listeners in the same manner through their own META-INF/spring.factories
properties
file.
Ordering TestExecutionListener
Implementations
When the TestContext framework discovers default TestExecutionListener
implementations
through the aforementioned
SpringFactoriesLoader
mechanism, the instantiated listeners are sorted by using
Spring’s AnnotationAwareOrderComparator
, which honors Spring’s Ordered
interface and
@Order
annotation for ordering. AbstractTestExecutionListener
and all default
TestExecutionListener
implementations provided by Spring implement Ordered
with
appropriate values. Third-party frameworks and developers should therefore make sure that
their default TestExecutionListener
implementations are registered in the proper order
by implementing Ordered
or declaring @Order
. See the javadoc for the getOrder()
methods of the core default TestExecutionListener
implementations for details on what
values are assigned to each core listener.
Merging TestExecutionListener
Implementations
If a custom TestExecutionListener
is registered via @TestExecutionListeners
, the
default listeners are not 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:
-
Java
-
Kotlin
@ContextConfiguration
@TestExecutionListeners({
MyCustomTestExecutionListener.class,
ServletTestExecutionListener.class,
DirtiesContextBeforeModesTestExecutionListener.class,
DependencyInjectionTestExecutionListener.class,
DirtiesContextTestExecutionListener.class,
TransactionalTestExecutionListener.class,
SqlScriptsTestExecutionListener.class
})
class MyTest {
// class body...
}
@ContextConfiguration
@TestExecutionListeners(
MyCustomTestExecutionListener::class,
ServletTestExecutionListener::class,
DirtiesContextBeforeModesTestExecutionListener::class,
DependencyInjectionTestExecutionListener::class,
DirtiesContextTestExecutionListener::class,
TransactionalTestExecutionListener::class,
SqlScriptsTestExecutionListener::class
)
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
Boot and Spring Security register their own default TestExecutionListener
implementations by using the aforementioned automatic discovery mechanism
.
To avoid having to be aware of and re-declare all default listeners, you can set the
mergeMode
attribute of @TestExecutionListeners
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 Ordering TestExecutionListener
Implementations.
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
are 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:
-
Java
-
Kotlin
@ContextConfiguration
@TestExecutionListeners(
listeners = MyCustomTestExecutionListener.class,
mergeMode = MERGE_WITH_DEFAULTS
)
class MyTest {
// class body...
}
@ContextConfiguration
@TestExecutionListeners(
listeners = [MyCustomTestExecutionListener::class],
mergeMode = MERGE_WITH_DEFAULTS
)
class MyTest {
// class body...
}