파이썬에서 **컨텍스트 매니저**는 `with` 문에서 사용할 수 있는 것입니다. 예를 들어, `open()`은 컨텍스트 매니저로 사용할 수 있습니다:

```Python
with open("file.txt") as file:
    file.read()
```
최근 버전의 파이썬에서는 **비동기 컨텍스트 매니저**도 있습니다. 이를 `async with`와 함께 사용합니다:

```Python
async with lifespan(app):
    await do_stuff()
```

컨텍스트 매니저나 위와 같은 비동기 컨텍스트 매니저를 만들면, `with` 블록에 들어가기 전에 `yield` 이전의 코드가 실행되고, `with` 블록을 벗어난 후에는 `yield` 이후의 코드가 실행됩니다.

type Decompressor func(r io.Reader) io.ReadCloser

var flateWriterPool sync.Pool

func newFlateWriter(w io.Writer) io.WriteCloser {
	fw, ok := flateWriterPool.Get().(*flate.Writer)
	if ok {
		fw.Reset(w)
	} else {
		fw, _ = flate.NewWriter(w, 5)
	}
	return &pooledFlateWriter{fw: fw}
}

type pooledFlateWriter struct {
	mu sync.Mutex // guards Close and Write
	fw *flate.Writer
}

      return sync.get();
    }

    @Override
    public boolean isDone() {
      return sync.isDone();
    }

    @Override
    public boolean isCancelled() {
      return sync.isCancelled();
    }

    @CanIgnoreReturnValue
    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
      if (!sync.cancel(mayInterruptIfRunning)) {

<details markdown="1">
<summary>Ya da <code>async def</code>...</summary>

Eğer kodunuzda `async` / `await` varsa, `async def` kullanalım:

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")

///

/// tip | Dica

Se você quiser chamar funções `async` em seus testes além de enviar solicitações ao seu aplicativo FastAPI (por exemplo, funções de banco de dados assíncronas), dê uma olhada em [Testes assíncronos](../advanced/async-tests.md){.internal-link target=_blank} no tutorial avançado.

///

## Separando testes

//// tab | Python 3.8+

```Python hl_lines="1"
async def needy_dependency(fresh_value: Annotated[str, Depends(get_value, use_cache=False)]):
    return {"fresh_value": fresh_value}
```

////

//// tab | Python 3.8+ nicht annotiert

/// tip | Tipp

Bevorzugen Sie die `Annotated`-Version, falls möglich.

///

```Python hl_lines="1"

```

<details markdown="1">
<summary>همچنین می‌توانید از <code>async def</code>... نیز استفاده کنید</summary>

اگر در کدتان از `async` / `await` استفاده می‌کنید، از `async def` برای تعریف تابع خود استفاده کنید:

```Python hl_lines="9  14"
from typing import Optional

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():
    return {"Hello": "World"}

        // Create a concrete implementation for comprehensive testing
        CommonServerMessageBlockResponse concreteResponse = new CommonServerMessageBlockResponse() {
            private boolean async = false;
            private CommonServerMessageBlockResponse next;
            private boolean received = false;
            private boolean error = false;
            private boolean verifyFailed = false;

Di kondisi ini, ini adalah sebuah fungsi `async`.

---

Anda bisa mendefinisikan fungsi ini sebagai fungsi normal daripada `async def`:

{* ../../docs_src/first_steps/tutorial003.py hl[7] *}

/// note | Catatan

Jika anda tidak tahu perbedaannya, kunjungi [Async: *"Panduan cepat"*](../async.md#in-a-hurry){.internal-link target=_blank}.

///

///

/// tip | Consejo

Si quieres llamar a funciones `async` en tus pruebas además de enviar solicitudes a tu aplicación FastAPI (por ejemplo, funciones asincrónicas de bases de datos), echa un vistazo a las [Pruebas Asincrónicas](../advanced/async-tests.md){.internal-link target=_blank} en el tutorial avanzado.

///

## Separando pruebas