### Before and after the `response`

You can add code to be run with the `request`,  before any *path operation* receives it.

And also after the `response` is generated, before returning it.

For example, you could add a custom header `X-Process-Time` containing the time in seconds that it took to process the request and generate a response:

For that, you use `app.add_middleware()` (as in the example for CORS).

```Python
from fastapi import FastAPI
from unicorn import UnicornMiddleware

app = FastAPI()

app.add_middleware(UnicornMiddleware, some_config="rainbow")
```

    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q


@app.post("/send-notification/{email}")
async def send_notification(
    email: str, background_tasks: BackgroundTasks, q: Annotated[str, Depends(get_query)]
):
    message = f"message to {email}\n"
    background_tasks.add_task(write_log, message)

So we add that line here, with the new file.

```Python hl_lines="16"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

## Dependency override

Now we create the dependency override and add it to the overrides for our app.

```Python hl_lines="19-24  27"

    for key, value in build_config.items():
        context.config.build_config[key] = value
    # Get main dependencies
    dependencies: List[str] = metadata.get("dependencies", [])
    # Add optional dependencies to the default dependencies for this (non-slim) package
    for include_optional in include_optional_dependencies:
        optional_dependencies_group = optional_dependencies.get(include_optional, [])

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

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

## Testing: extended example

Now let's extend this example and add more details to see how to test different parts.

### Extended **FastAPI** app file

Let's continue with the same file structure as before:

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

```Python hl_lines="6-9"
{!../../../docs_src/background_tasks/tutorial001.py!}
```

## バックグラウンドタスクの追加

*path operations 関数* 内で、`.add_task()` メソッドを使用してタスク関数を *background tasks* オブジェクトに渡します。

```Python hl_lines="14"
{!../../../docs_src/background_tasks/tutorial001.py!}
```

`.add_task()` は以下の引数を受け取ります:

* バックグラウンドで実行されるタスク関数 (`write_notification`)。
* タスク関数に順番に渡す必要のある引数の列 (`email`)。

    * If you didn't use FastAPI and used Starlette directly (or another tool, like Sanic, Flask, Responder, etc) you would have to implement all the data validation and serialization...

## 디버거로 코드 실행

코드에서 직접 Uvicorn 서버를 실행하고 있기 때문에 디버거에서 직접 Python 프로그램(FastAPI 애플리케이션)을 호출할 수 있습니다.

---

예를 들어 Visual Studio Code에서 다음을 수행할 수 있습니다.

* "Debug" 패널로 이동합니다.
* "Add configuration...".
* "Python"을 선택합니다.
* "`Python: Current File (Integrated Terminal)`" 옵션으로 디버거를 실행합니다.

그런 다음 **FastAPI** 코드로 서버를 시작하고 중단점 등에서 중지합니다.

다음과 같이 표시됩니다.

<img src="/img/tutorial/debugging/image01.png">

!!! tip
    Notice how each model's attribute with a type, default value and `Field` has the same structure as a *path operation function's* parameter, with `Field` instead of `Path`, `Query` and `Body`.

## Add extra information

You can declare extra information in `Field`, `Query`, `Body`, etc. And it will be included in the generated JSON Schema.