- deployment/docker.md
  - How To - Recipes:
    - how-to/index.md
    - how-to/general.md
    - how-to/migrate-from-pydantic-v1-to-pydantic-v2.md
    - how-to/graphql.md
    - how-to/custom-request-and-route.md
    - how-to/conditional-openapi.md
    - how-to/extending-openapi.md
    - how-to/separate-openapi-schemas.md
    - how-to/custom-docs-ui-assets.md
    - how-to/configure-swagger-ui.md

This code won't be executed in your app, we only need it to *document* how that *external API* should look like.

But, you already know how to easily create automatic documentation for an API with **FastAPI**.

{* ../../docs_src/app_testing/app_b_an_py310/test_main.py *}


Whenever you need the client to pass information in the request and you don't know how to, you can search (Google) how to do it in `httpx`, or even how to do it with `requests`, as HTTPX's design is based on Requests' design.

Then you just do the same in your tests.

E.g.:

# Advanced Middleware { #advanced-middleware }

In the main tutorial you read how to add [Custom Middleware](../tutorial/middleware.md){.internal-link target=_blank} to your application.

And then you also read how to handle [CORS with the `CORSMiddleware`](../tutorial/cors.md){.internal-link target=_blank}.

In this section we'll see how to use other middlewares.

## Adding ASGI middlewares { #adding-asgi-middlewares }

## Dependencies for groups of *path operations* { #dependencies-for-groups-of-path-operations }

Let's see how to make use of a custom `Request` subclass to decompress gzip requests.

And an `APIRoute` subclass to use that custom request class.

### Create a custom `GzipRequest` class { #create-a-custom-gziprequest-class }

/// tip

# Async Tests { #async-tests }

You have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

        Provide a brief summary of the issue in the title above
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us how it should work
    validations:
      required: true
  - type: textarea
    id: current-behavior
    attributes:
      label: Current Behavior (optional)

Now, let's see how you could use that to return a custom response.

Let's say that you want to return an <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> response.

So we use a relative import with `..` for the dependencies:

{* ../../docs_src/bigger_applications/app_an_py39/routers/items.py hl[3] title["app/routers/items.py"] *}

#### How relative imports work { #how-relative-imports-work }

/// tip

If you know perfectly how imports work, continue to the next section below.

///

A single dot `.`, like in:

```Python
from .dependencies import get_token_header
```