uses: actions/setup-python@v5
        with:
          python-version: "3.10"
          # Issue ref: https://github.com/actions/setup-python/issues/436
          # cache: "pip"
          # cache-dependency-path: pyproject.toml
      - name: Install build dependencies
        run: pip install build
      - name: Build distribution
        env:
          TIANGOLO_BUILD_PACKAGE: ${{ matrix.package }}

一般只要测试一次外部验证应用就够了，不必每次测试都去调用。

此时，最好覆盖调用外部验证应用的依赖项，使用返回模拟测试用户的自定义依赖项就可以了。

### 使用 `app.dependency_overrides` 属性

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。

Es ist so konzipiert, sehr einfach zu verwenden zu sein und es jedem Entwickler sehr leicht zu machen, andere Komponenten mit **FastAPI** zu integrieren.

## Was ist „Dependency Injection“

Она проектировалась таким образом, чтобы быть простой в использовании и облегчить любому разработчику интеграцию других компонентов с **FastAPI**.

## Что такое "Dependency Injection" (инъекция зависимости)

**FastAPI** 🔜 ⚒ 💭 👈 "🚪 📟" 🔠 🔗 ⏮️ `yield` 🏃 ☑ ✔.

🖼, `dependency_c` 💪 ✔️ 🔗 🔛 `dependency_b`, & `dependency_b` 🔛 `dependency_a`:

```Python hl_lines="4  12  20"
{!../../../docs_src/dependencies/tutorial008.py!}
```

& 🌐 👫 💪 ⚙️ `yield`.

👉 💼 `dependency_c`, 🛠️ 🚮 🚪 📟, 💪 💲 ⚪️➡️ `dependency_b` (📥 📛 `dep_b`) 💪.

& , 🔄, `dependency_b` 💪 💲 ⚪️➡️ `dependency_a` (📥 📛 `dep_a`) 💪 🚮 🚪 📟.

    ```

This dependency will provide a `str` that is assigned to the parameter `token` of the *path operation function*.

**FastAPI** will know that it can use this dependency to define a "security scheme" in the OpenAPI schema (and the automatic API docs).

!!! info "Technical Details"

Base.metadata.create_all(bind=engine)


def override_get_db():
    try:
        db = TestingSessionLocal()
        yield db
    finally:
        db.close()


app.dependency_overrides[get_db] = override_get_db

client = TestClient(app)


def test_create_user():
    response = client.post(
        "/users/",

### Einbringen von Abhängigkeiten (Dependency Injection)

FastAPI enthält ein extrem einfach zu verwendendes, aber extrem mächtiges <abbr title='Dependency Injection – Einbringen von Abhängigkeiten: Auch bekannt als Komponenten, Resourcen, Dienste, Dienstanbieter'><strong>Dependency Injection</strong></abbr> System.

* Alle Schlüsselwort-Argumente, die an die Taskfunktion übergeben werden sollen (`message="some notification"`).

## Dependency Injection

This is quite simple (not very useful), but will help us focus on how the sub-dependencies work.

## Second dependency, "dependable" and "dependant"

Then you can create another dependency function (a "dependable") that at the same time declares a dependency of its own (so it is a "dependant" too):

=== "Python 3.10+"

    ```Python hl_lines="13"