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Improve documentation for ApplicationEvents to clarify recommended usage

See gh-35335
pull/35405/head
Sam Brannen 4 months ago
parent
commit
19d5ec6781
  1. 39
      framework-docs/modules/ROOT/pages/testing/testcontext-framework/application-events.adoc
  2. 15
      spring-test/src/main/java/org/springframework/test/context/event/ApplicationEvents.java

39
framework-docs/modules/ROOT/pages/testing/testcontext-framework/application-events.adoc

@ -16,12 +16,19 @@ To use `ApplicationEvents` in your tests, do the following. @@ -16,12 +16,19 @@ To use `ApplicationEvents` in your tests, do the following.
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 xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[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.
* When using the
xref:testing/testcontext-framework/support-classes.adoc#testcontext-junit-jupiter-extension[SpringExtension for JUnit Jupiter],
declare a method parameter of type `ApplicationEvents` in a `@Test`, `@BeforeEach`, or
`@AfterEach` method.
** Since `ApplicationEvents` is scoped to the lifecycle of the current test method, this
is the recommended approach.
* Alternatively, you can annotate a field of type `ApplicationEvents` with `@Autowired`
and use that instance of `ApplicationEvents` in your test and lifecycle methods.
NOTE: `ApplicationEvents` is registered with the `ApplicationContext` as a _resolvable
dependency_ which is scoped to the lifecycle of the current test method. Consequently,
`ApplicationEvents` cannot be accessed outside the lifecycle of a test method and cannot be
`@Autowired` into the constructor of a test class.
The following test class uses the `SpringExtension` for JUnit Jupiter and
{assertj-docs}[AssertJ] to assert the types of application events published while
@ -38,16 +45,10 @@ Java:: @@ -38,16 +45,10 @@ Java::
@RecordApplicationEvents // <1>
class OrderServiceTests {
@Autowired
OrderService orderService;
@Autowired
ApplicationEvents events; // <2>
@Test
void submitOrder() {
void submitOrder(@Autowired OrderService service, ApplicationEvents events) { // <2>
// Invoke method in OrderService that publishes an event
orderService.submitOrder(new Order(/* ... */));
service.submitOrder(new Order(/* ... */));
// Verify that an OrderSubmitted event was published
long numEvents = events.stream(OrderSubmitted.class).count(); // <3>
assertThat(numEvents).isEqualTo(1);
@ -66,16 +67,10 @@ Kotlin:: @@ -66,16 +67,10 @@ Kotlin::
@RecordApplicationEvents // <1>
class OrderServiceTests {
@Autowired
lateinit var orderService: OrderService
@Autowired
lateinit var events: ApplicationEvents // <2>
@Test
fun submitOrder() {
fun submitOrder(@Autowired service: OrderService, events: ApplicationEvents) { // <2>
// Invoke method in OrderService that publishes an event
orderService.submitOrder(Order(/* ... */))
service.submitOrder(Order(/* ... */))
// Verify that an OrderSubmitted event was published
val numEvents = events.stream(OrderSubmitted::class).count() // <3>
assertThat(numEvents).isEqualTo(1)

15
spring-test/src/main/java/org/springframework/test/context/event/ApplicationEvents.java

@ -34,15 +34,20 @@ import org.springframework.context.ApplicationEvent; @@ -34,15 +34,20 @@ import org.springframework.context.ApplicationEvent;
* {@link org.springframework.test.context.TestExecutionListeners @TestExecutionListeners}
* that does not include the default listeners.</li>
* <li>With JUnit Jupiter, declare a parameter of type {@code ApplicationEvents}
* in a test or lifecycle method. Since {@code ApplicationEvents} is scoped to the
* lifecycle of the current test method, this is the recommended approach.</li>
* in a {@code @Test}, {@code @BeforeEach}, or {@code @AfterEach} method. Since
* {@code ApplicationEvents} is scoped to the lifecycle of the current test method,
* this is the recommended approach.</li>
* <li>Alternatively, you can annotate a field of type {@code ApplicationEvents} with
* {@link org.springframework.beans.factory.annotation.Autowired @Autowired} and
* use that instance of {@code ApplicationEvents} in your test and lifecycle methods.
* Note that {@code ApplicationEvents} is not a general Spring bean and is specifically
* designed for use within test methods.</li>
* use that instance of {@code ApplicationEvents} in your test and lifecycle methods.</li>
* </ul>
*
* <p>NOTE: {@code ApplicationEvents} is registered with the {@code ApplicationContext} as a
* {@linkplain org.springframework.beans.factory.config.ConfigurableListableBeanFactory#registerResolvableDependency
* resolvable dependency} which is scoped to the lifecycle of the current test method.
* Consequently, {@code ApplicationEvents} cannot be accessed outside the lifecycle of a
* test method and cannot be {@code @Autowired} into the constructor of a test class.
*
* @author Sam Brannen
* @author Oliver Drotbohm
* @since 5.3.3

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