- Insert a debug container in clusters that don’t have ephemeral containers enabled 
 - Modify a crashing container for easier debugging by changing its image, for example to busybox, or its command, for example, to `sleep 1d` so you have time to `kubectl exec`.
 - Inspect configuration files on a node's host filesystem

The `TestClient` is based on <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>, and luckily, we can use it directly to test the API.

## Example { #example }

For a simple example, let's consider a file structure similar to the one described in [Bigger Applications](../tutorial/bigger-applications.md){.internal-link target=_blank} and [Testing](../tutorial/testing.md){.internal-link target=_blank}:

    "tax": 3.2,
    "tags": [
        "rock",
        "metal",
        "bar"
    ],
    "images": [
        {
            "url": "http://example.com/baz.jpg",
            "name": "The Foo live"
        },
        {
            "url": "http://example.com/dave.jpg",
            "name": "The Baz"
        }
    ]
}
```

/// info

{* ../../docs_src/app_testing/app_a_py39/test_main.py hl[3] *}


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

## Testing: extended example { #testing-extended-example }

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

### Extended **FastAPI** app file { #extended-fastapi-app-file }

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

## How to enable Fan-Out Uploads ?

Fan-Out uploads are automatically enabled if `x-minio-fanout-list` form-field is provided with the PostUpload API, to keep things simple higher level APIs are provided in our SDKs for example in `minio-go` SDK:

```
PutObjectFanOut(ctx context.Context, bucket string, fanOutContent io.Reader, fanOutReq minio.PutObjectFanOutRequest) ([]minio.PutObjectFanOutResponse, error)

That's why in this example we have to declare it in the `response_model` parameter.

...but continue reading below to see how to overcome that.

## Return Type and Data Filtering { #return-type-and-data-filtering }

* `allow_origins` - Список источников, на которые разрешено выполнять кросс-доменные запросы. Например, `['https://example.org', 'https://www.example.org']`. Можно использовать `['*']`, чтобы разрешить любые источники.
* `allow_origin_regex` - Регулярное выражение для определения источников, на которые разрешено выполнять кросс-доменные запросы. Например, `'https://.*\.example\.org'`.

///

{* ../../docs_src/extra_models/tutorial003_py310.py hl[1,14:15,18:20,33] *}

### `Union` in Python 3.10 { #union-in-python-3-10 }

In this example we pass `Union[PlaneItem, CarItem]` as the value of the argument `response_model`.

## Use Case { #use-case }

Let's start with an example **use case** and then see how to solve it with this.

Let's imagine that you have some **machine learning models** that you want to use to handle requests. 🤖

* `allow_origin_regex` - Una cadena regex para coincidir con orígenes que deberían estar permitidos para hacer requests cross-origin. por ejemplo, `'https://.*\.example\.org'`.