Параметр `lifespan` приложения `FastAPI` принимает асинхронный менеджер контекста, поэтому мы можем передать ему наш новый асинхронный менеджер контекста `lifespan`.

{* ../../docs_src/events/tutorial003_py39.py hl[22] *}

## Альтернативные события (устаревшие) { #alternative-events-deprecated }

/// warning | Предупреждение

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。

Diese Funktionen können mit `async def` oder normalem `def` deklariert werden.

### `startup`-Event { #startup-event }

Um eine Funktion hinzuzufügen, die vor dem Start der Anwendung ausgeführt werden soll, deklarieren Sie diese mit dem Event `startup`:

{* ../../docs_src/events/tutorial001_py39.py hl[8] *}

### Evento `shutdown` { #shutdown-event }

Para adicionar uma função que deve ser executada quando a aplicação estiver encerrando, declare-a com o evento `"shutdown"`:

{* ../../docs_src/events/tutorial002_py39.py hl[6] *}

Aqui, a função de manipulador do evento `shutdown` escreverá uma linha de texto `"Application shutdown"` no arquivo `log.txt`.

/// info | Informação

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event { #shutdown-event }

To add a function that should be run when the application is shutting down, declare it with the event `"shutdown"`:

### Evento `shutdown` { #shutdown-event }

Para añadir una función que debería ejecutarse cuando la aplicación se esté cerrando, declárala con el evento `"shutdown"`:

{* ../../docs_src/events/tutorial002_py39.py hl[6] *}

Aquí, la función manejadora del evento `shutdown` escribirá una línea de texto `"Application shutdown"` a un archivo `log.txt`.

/// info | Información

![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

{* ../../docs_src/events/tutorial003.py hl[14:19] *}

함수의 첫 번째 부분, 즉 `yield` 이전의 코드는 애플리케이션이 시작되기 **전에** 실행됩니다.

그리고 `yield` 이후의 부분은 애플리케이션이 완료된 후 **나중에** 실행됩니다.

### 비동기 컨텍스트 매니저

함수를 확인해보면, `@asynccontextmanager`로 장식되어 있습니다.

이것은 함수를 "**비동기 컨텍스트 매니저**"라고 불리는 것으로 변환시킵니다.

{* ../../docs_src/events/tutorial003.py hl[1,13] *}

events@2x.png...

# 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)