* `File()`

you can also declare a group of `examples` with additional information that will be added to their **JSON Schemas** inside of **OpenAPI**.

### `Body` with `examples` { #body-with-examples }

Here we pass `examples` containing one example of the data expected in `Body()`:

{* ../../docs_src/schema_extra_example/tutorial003_an_py310.py hl[22:29] *}

### Example in the docs UI { #example-in-the-docs-ui }

# Testen { #testing }

Dank [Starlette](https://www.starlette.dev/testclient/) ist das Testen von **FastAPI**-Anwendungen einfach und macht Spaß.

Es basiert auf [HTTPX](https://www.python-httpx.org), welches wiederum auf der Grundlage von Requests konzipiert wurde, es ist also sehr vertraut und intuitiv.

Damit können Sie [pytest](https://docs.pytest.org/) direkt mit **FastAPI** verwenden.

## `TestClient` verwenden { #using-testclient }

/// info | Info

* Create a `templates` object that you can reuse later.
* Declare a `Request` parameter in the *path operation* that will return a template.
* Use the `templates` you created to render and return a `TemplateResponse`, pass the name of the template, the request object, and a "context" dictionary with key-value pairs to be used inside of the Jinja2 template.

{* ../../docs_src/templates/tutorial001_py310.py hl[4,11,15:18] *}

/// note

  {{.HelpName}} {{if .VisibleFlags}}[FLAGS] {{end}}DIR{1...64} DIR{65...128}

DIR:
  DIR points to a directory on a filesystem. When you want to combine
  multiple drives into a single large system, pass one directory per
  filesystem separated by space. You may also use a '...' convention
  to abbreviate the directory arguments. Remote directories in a
  distributed setup are encoded as HTTP(s) URIs.
{{if .VisibleFlags}}

    sendRequest(client, "https://valid-isrgrootx1.letsencrypt.org/robots.txt");

    try {
      sendRequest(client, "https://google.com/robots.txt");
      if (androidMorEarlier) {
        // will pass with default CAs on N or later
        fail();
      }
    } catch (SSLHandshakeException sslhe) {
      assertTrue(androidMorEarlier);
    }
  }

  fun expectParseFailure() = scheme.isEmpty()

  private operator fun set(
    name: String,
    value: String,
  ) {
    when (name) {
      "s" -> scheme = value
      "u" -> username = value
      "pass" -> password = value
      "h" -> host = value
      "port" -> port = value
      "p" -> path = value
      "q" -> query = value
      "f" -> fragment = value

```JSON
{
  "detail": "Item not found"
}
```

/// tip

When raising an `HTTPException`, you can pass any value that can be converted to JSON as the parameter `detail`, not only `str`.

You could pass a `dict`, a `list`, etc.

They are handled automatically by **FastAPI** and converted to JSON.

///

## Add custom headers { #add-custom-headers }

  }

  /**
   * Returns a cache loader that uses {@code function} to load keys, and without supporting either
   * reloading or bulk loading. This is most useful when you can pass a lambda expression. Otherwise
   * it is useful mostly when you already have an existing function instance.
   *
   * <p>The returned object is serializable if {@code function} is serializable.
   *

There are 2 main differences from a normal *path operation*:

* It doesn't need to have any actual code, because your app will never call this code. It's only used to document the *external API*. So, the function could just have `pass`.

### Include the custom docs { #include-the-custom-docs }

Now you can create the *path operations* for the custom docs.

You can reuse FastAPI's internal functions to create the HTML pages for the docs, and pass them the needed arguments:

* `openapi_url`: the URL where the HTML page for the docs can get the OpenAPI schema for your API. You can use here the attribute `app.openapi_url`.
* `title`: the title of your API.