Application Events

Since Spring Framework 5.3.3, the TestContext framework provides support for recording application events published in the ApplicationContext so that assertions can be performed against those events within tests. All events published during the execution of a single test are made available via the ApplicationEvents API which allows you to process the events as a java.util.Stream.

To use ApplicationEvents in your tests, do the following.

  • Ensure that your test class is annotated or meta-annotated with @RecordApplicationEvents.

  • Ensure that the ApplicationEventsTestExecutionListener is registered. Note, however, that ApplicationEventsTestExecutionListener is registered by default and only needs to be manually registered if you have custom configuration via @TestExecutionListeners that does not include the default listeners.

  • Annotate a field of type ApplicationEvents with @Autowired and use that instance of ApplicationEvents in your test and lifecycle methods (such as @BeforeEach and @AfterEach methods in JUnit Jupiter).

    • When using the SpringExtension for JUnit Jupiter, you may declare a method parameter of type ApplicationEvents in a test or lifecycle method as an alternative to an @Autowired field in the test class.

The following test class uses the SpringExtension for JUnit Jupiter and AssertJ to assert the types of application events published while invoking a method in a Spring-managed component:

  • Java

  • Kotlin

@SpringJUnitConfig(/* ... */)
@RecordApplicationEvents (1)
class OrderServiceTests {

	@Autowired
	OrderService orderService;

	@Autowired
	ApplicationEvents events; (2)

	@Test
	void submitOrder() {
		// Invoke method in OrderService that publishes an event
		orderService.submitOrder(new Order(/* ... */));
		// Verify that an OrderSubmitted event was published
		long numEvents = events.stream(OrderSubmitted.class).count(); (3)
		assertThat(numEvents).isEqualTo(1);
	}
}
1 Annotate the test class with @RecordApplicationEvents.
2 Inject the ApplicationEvents instance for the current test.
3 Use the ApplicationEvents API to count how many OrderSubmitted events were published. 
@SpringJUnitConfig(/* ... */)
@RecordApplicationEvents (1)
class OrderServiceTests {

	@Autowired
	lateinit var orderService: OrderService

	@Autowired
	lateinit var events: ApplicationEvents (2)

	@Test
	fun submitOrder() {
		// Invoke method in OrderService that publishes an event
		orderService.submitOrder(Order(/* ... */))
		// Verify that an OrderSubmitted event was published
		val numEvents = events.stream(OrderSubmitted::class).count() (3)
		assertThat(numEvents).isEqualTo(1)
	}
}
1 Annotate the test class with @RecordApplicationEvents.
2 Inject the ApplicationEvents instance for the current test.
3 Use the ApplicationEvents API to count how many OrderSubmitted events were published.

See the ApplicationEvents javadoc for further details regarding the ApplicationEvents API.