type GetObjectContext struct {
	OutputRoute string `json:"outputRoute"`
	OutputToken string `json:"outputToken"`
	InputS3URL  string `json:"inputS3Url"`
}

// Event represents lambda function event, this is undocumented in AWS S3. This
// structure bases itself on this structure but there is no binding.
//
//	{
//	  "xAmzRequestId": "a2871150-1df5-4dc9-ad9f-3da283ca1bf3",
//	  "getObjectContext": {
//	    "outputRoute": "...",

首先要注意的是，我们定义了一个带有 `yield` 的异步函数。这与带有 `yield` 的依赖项非常相似。

```Python hl_lines="14-19"
{!../../docs_src/events/tutorial003.py!}
```

这个函数在 `yield`之前的部分，会在应用启动前执行。

剩下的部分在 `yield` 之后，会在应用完成后执行。

## 异步上下文管理器

如你所见，这个函数有一个装饰器 `@asynccontextmanager` 。

它将函数转化为所谓的“**异步上下文管理器**”。

```Python hl_lines="1  13"
{!../../docs_src/events/tutorial003.py!}
```

在 Python 中，  **上下文管理器**是一个你可以在 `with` 语句中使用的东西，例如，`open()` 可以作为上下文管理器使用。

![Events Diagram](../assets/images/events@2x.png)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertEvent(
    id: String?,
    type: String?,
    data: String,
  ) {
    assertThat(nextEvent()).isEqualTo(Event(id, type, data))
  }

  fun assertOpen(): EventSource {
    val event = nextEvent() as Open
    return event.eventSource
  }

  fun assertClose() {
    nextEvent() as Closed
  }

  fun assertFailure(

    public void projectSkipped(ExecutionEvent event) {
        dispatcher.onEvent(event);
        delegate.projectSkipped(event);
    }

    @Override
    public void projectStarted(ExecutionEvent event) {
        dispatcher.onEvent(event);
        delegate.projectStarted(event);
    }

    @Override
    public void projectSucceeded(ExecutionEvent event) {
        dispatcher.onEvent(event);
        delegate.projectSucceeded(event);

        dispatcher.onEvent(event);
        delegate.artifactInstalling(event);
    }

    @Override
    public void artifactResolved(RepositoryEvent event) {
        dispatcher.onEvent(event);
        delegate.artifactResolved(event);
    }

    @Override
    public void artifactResolving(RepositoryEvent event) {
        dispatcher.onEvent(event);
        delegate.artifactResolving(event);
    }

    @Override

			// Defensive code, should never happen
			if obj.VersionID == "" {
				event.Action = NoneAction
			}
			if e.IsObjectLocked(obj) {
				event = Event{}
			}

			if e.IsPendingReplication(obj) {
				event = Event{}
			}
		}
		if !obj.IsLatest {
			switch event.Action {
			case DeleteVersionAction:
				// this noncurrent version will be expired, nothing to add
			default:

# Testing Events: lifespan and startup - shutdown { #testing-events-lifespan-and-startup-shutdown }

When you need `lifespan` to run in your tests, you can use the `TestClient` with a `with` statement:

{* ../../docs_src/app_testing/tutorial004_py39.py hl[9:15,18,27:28,30:32,41:43] *}


You can read more details about the ["Running lifespan in tests in the official Starlette documentation site."](https://www.starlette.dev/lifespan/#running-lifespan-in-tests)

events@2x.png...

import org.apache.maven.api.annotations.Nonnull;

/**
 * A listener for session events.
 * TODO: open this to other events like similar to {@code org.apache.maven.eventspy.EventSpy}
 *
 * @since 4.0.0
 */
@Experimental
@FunctionalInterface
@Consumer
public interface Listener {
    void onEvent(@Nonnull Event event);