You can use the same dependency overrides from [Testing Dependencies with Overrides](testing-dependencies.md){.internal-link target=_blank} to alter a database for testing.

You could want to set up a different database for testing, rollback the data after the tests, pre-fill it with some testing data, etc.

You can import it directly from `fastapi`:

```python
from fastapi import Request
```

!!! tip
    When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

* 所有的这些*路径操作*都将在自身之前计算/执行 `dependencies` 列表。
    * 如果你还在一个具体的*路径操作*中声明了依赖项，**它们也会被执行**。
    * 路由器的依赖项最先执行，然后是[装饰器中的 `dependencies`](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}，再然后是普通的参数依赖项。
    * 你还可以添加[具有 `scopes` 的 `Security` 依赖项](../advanced/security/oauth2-scopes.md){.internal-link target=_blank}。

!!! tip
    在 `APIRouter`中具有 `dependencies` 可以用来，例如，对一整组的*路径操作*要求身份认证。即使这些依赖项并没有分别添加到每个路径操作中。

=== "Python 3.10+"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="8-11"
    {!> ../../../docs_src/dependencies/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9-12"
    {!> ../../../docs_src/dependencies/tutorial001_an.py!}
    ```

=== "Python 3.10+ nicht annotiert"

=== "Python 3.10+"

    ```Python hl_lines="8-9"
    {!> ../../../docs_src/dependencies/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="8-11"
    {!> ../../../docs_src/dependencies/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9-12"
    {!> ../../../docs_src/dependencies/tutorial001_an.py!}
    ```

=== "Python 3.10+ non-Annotated"

        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 }}
        run: python -m build
      - name: Publish

    "W191",  # indentation contains tabs
]

[tool.ruff.lint.per-file-ignores]
"__init__.py" = ["F401"]
"docs_src/dependencies/tutorial007.py" = ["F821"]
"docs_src/dependencies/tutorial008.py" = ["F821"]
"docs_src/dependencies/tutorial009.py" = ["F821"]
"docs_src/dependencies/tutorial010.py" = ["F821"]
"docs_src/custom_response/tutorial007.py" = ["B007"]
"docs_src/dataclasses/tutorial003.py" = ["I001"]

def test_internal_error(client: TestClient):
    from docs_src.dependencies.tutorial008d import InternalError

    with pytest.raises(InternalError) as exc_info:
        client.get("/items/portal-gun")
    assert (
        exc_info.value.args[0] == "The portal gun is too dangerous to be owned by Rick"
    )


def test_internal_server_error():
    from docs_src.dependencies.tutorial008d import app

    ✋️ 🔚, 👫 🛠️ 🎏 Oauth2️⃣ 🐩.

**FastAPI** 🔌 🚙 🌐 👫 Oauth2️⃣ 🤝 💧 `fastapi.security.oauth2`.

## `Security` 👨‍🎨 `dependencies`

        self.query_params = query_params or []
        self.header_params = header_params or []
        self.cookie_params = cookie_params or []
        self.body_params = body_params or []
        self.dependencies = dependencies or []
        self.security_requirements = security_schemes or []
        self.request_param_name = request_param_name
        self.websocket_param_name = websocket_param_name