}

app = FastAPI()


class Item(BaseModel):
    id: str
    title: str
    description: Union[str, None] = None


@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header()):
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="Invalid X-Token header")
    if item_id not in fake_db:

from fastapi.testclient import TestClient

from .main import app

client = TestClient(app)


def test_read_item():
    response = client.get("/items/foo", headers={"X-Token": "coneofsilence"})
    assert response.status_code == 200
    assert response.json() == {
        "id": "foo",
        "title": "Foo",
        "description": "There goes my hero",
    }


def test_read_item_bad_token():

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()

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

Because this file is in the same package, you can use relative imports to import the object `app` from the `main` module (`main.py`):

```Python hl_lines="3"
{!../../../docs_src/app_testing/test_main.py!}
```

...and have the code for the tests just like before.

## Testing: extended example

    </div>

!!! note
    The command `uvicorn main:app` refers to:

    * `main`: the file `main.py` (the Python "module").
    * `app`: the object created inside of `main.py` with the line `app = FastAPI()`.

    It is equivalent to:

    ```Python
    from main import app
    ```

!!! warning
    Uvicorn and others support a `--reload` option that is useful during development.

def deep_dict_update(main_dict: Dict[Any, Any], update_dict: Dict[Any, Any]) -> None:
    for key, value in update_dict.items():
        if (
            key in main_dict
            and isinstance(main_dict[key], dict)
            and isinstance(value, dict)
        ):
            deep_dict_update(main_dict[key], value)
        elif (
            key in main_dict

## `uvicorn` 호출

FastAPI 애플리케이션에서 `uvicorn`을 직접 임포트하여 실행합니다

```Python hl_lines="1  15"
{!../../../docs_src/debugging/tutorial001.py!}
```

### `__name__ == "__main__"` 에 대하여

`__name__ == "__main__"`의 주요 목적은 다음과 같이 파일이 호출될 때 실행되는 일부 코드를 갖는 것입니다.

<div class="termy">

```console
$ python myapp.py
```

</div>

그러나 다음과 같이 다른 파일을 가져올 때는 호출되지 않습니다.

```Python

    # Get main optional dependencies, extras
    optional_dependencies: Dict[str, List[str]] = metadata.get(
        "optional-dependencies", {}
    )
    # Get custom optional dependencies name to always include in this (non-slim) package
    include_optional_dependencies: List[str] = config.get(
        "include-optional-dependencies", []
    )

<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

!!! note
    📋 `uvicorn main:app` 🔗:

    * `main`: 📁 `main.py` (🐍 "🕹").
    * `app`: 🎚 ✍ 🔘 `main.py` ⏮️ ⏸ `app = FastAPI()`.
    * `--reload`: ⚒ 💽 ⏏ ⏮️ 📟 🔀. 🕴 ⚙️ 🛠️.

🔢, 📤 ⏸ ⏮️ 🕳 💖:

```hl_lines="4"

        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - uses: actions/checkout@v4
        with:
          # To allow latest-changes to commit to the main branch
          token: ${{ secrets.FASTAPI_LATEST_CHANGES }}
      # Allow debugging with tmate
      - name: Setup tmate session
        uses: mxschmitt/action-tmate@v3