=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}
    ```

=== "Python 3.9+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py39/main.py!}
    ```

=== "Python 3.8+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an/main.py!}
    ```

=== "Python 3.10+ non-Annotated"

    !!! tip

from docs_src.app_testing.app_b_an import test_main


def test_app():
    test_main.test_create_existing_item()
    test_main.test_create_item()
    test_main.test_create_item_bad_token()
    test_main.test_read_nonexistent_item()
    test_main.test_read_item()

## Testing locally with Traefik

You can easily run the experiment locally with a stripped path prefix using <a href="https://docs.traefik.io/" class="external-link" target="_blank">Traefik</a>.

    And after searching for a long time for a similar framework and testing many different alternatives, APIStar was the best option available.

对于这些用例，**FastAPI** 应用支持 `app.dependcy_overrides` 属性，该属性就是**字典**。

要在测试时覆盖原有依赖项，这个字典的键应当是原依赖项（函数），值是覆盖依赖项（另一个函数）。

这样一来，**FastAPI** 就会调用覆盖依赖项，不再调用原依赖项。

```Python hl_lines="26-27  30"
{!../../../docs_src/dependency_testing/tutorial001.py!}
```

!!! tip "提示"

    **FastAPI** 应用中的任何位置都可以实现覆盖依赖项。

    原依赖项可用于*路径操作函数*、*路径操作装饰器*（不需要返回值时）、`.include_router()` 调用等。

    FastAPI 可以覆盖这些位置的依赖项。

## Beispiel

Betrachten wir als einfaches Beispiel eine Dateistruktur ähnlich der in [Größere Anwendungen](../tutorial/bigger-applications.md){.internal-link target=_blank} und [Testen](../tutorial/testing.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

Die Datei `main.py` hätte als Inhalt:

```Python

* Update docs for testing FastAPI. Include using `POST`, sending JSON, testing headers, etc. New documentation: [Testing](https://fastapi.tiangolo.com/tutorial/testing/#testing-extended-example). PR [#271](https://github.com/tiangolo/fastapi/pull/271).

=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}
    ```

=== "Python 3.9+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py39/main.py!}
    ```

=== "Python 3.8+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an/main.py!}
    ```

=== "Python 3.10+ nicht annotiert"

    !!! tip "Tipp"

```Python hl_lines="27-31"
{!../../../docs_src/app_testing/tutorial002.py!}
```

!!! note "Hinweis"

Wenn Sie in Ihren Tests Ihre Event-Handler (`startup` und `shutdown`) ausführen wollen, können Sie den `TestClient` mit einer `with`-Anweisung verwenden:

```Python hl_lines="9-12  20-24"
{!../../../docs_src/app_testing/tutorial003.py!}