bufferHelper("three\rlines\rno newline at end", "three\r", "lines\r", "no newline at end");
    bufferHelper("mixed\nline\rendings\r\n", "mixed\n", "line\r", "endings\r\n");
  }

  private static final int[] CHUNK_SIZES = {1, 2, 3, Integer.MAX_VALUE};

  private static void bufferHelper(String input, String... expect) throws IOException {

    bufferHelper("three\rlines\rno newline at end", "three\r", "lines\r", "no newline at end");
    bufferHelper("mixed\nline\rendings\r\n", "mixed\n", "line\r", "endings\r\n");
  }

  private static final int[] CHUNK_SIZES = {1, 2, 3, Integer.MAX_VALUE};

  private static void bufferHelper(String input, String... expect) throws IOException {

This includes, for example:

* Email notifications sent after performing an action:
    * As connecting to an email server and sending an email tends to be "slow" (several seconds), you can return the response right away and send the email notification in the background.
* Processing data:

        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    """

    def __init__(

Being able to use asynchronous functions in your tests could be useful, for example, when you're querying your database asynchronously. Imagine you want to test sending requests to your FastAPI application and then verify that your backend successfully wrote the correct data in the database, while using an async database library.

Let's look at how we can make that work.

## pytest.mark.anyio

# Always check-out / check-in files with LF line endings.
* text=auto eol=lf

hack/verify-flags/known-flags.txt merge=union
test/test_owners.csv merge=union

**/zz_generated.*.go linguist-generated=true
**/types.generated.go linguist-generated=true
**/generated.pb.go linguist-generated=true
**/generated.proto
**/types_swagger_doc_generated.go linguist-generated=true
api/openapi-spec/*.json linguist-generated=true

# OpenAPI Webhooks

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps

So, you will have to make sure your data is of the correct type. E.g. it is compatible with JSON, if you are returning a `JSONResponse`.

And also that you are not sending any data that should have been filtered by a `response_model`.

///

### More info

/// note | "Technical Details"

The process that happens when your API app calls the *external API* is named a "callback". Because the software that the external developer wrote sends a request to your API and then your API *calls back*, sending a request to an *external API* (that was probably created by the same developer).

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="9"
{!> ../../docs_src/header_params/tutorial003.py!}
```

////

If you communicate with that *path operation* sending two HTTP headers like:

```
X-Token: foo
X-Token: bar
```

The response would be like:

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```