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.

# OpenAPI Webhooks { #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**.

/// info

Added in FastAPI 0.134.0.

///

## What is a Stream? { #what-is-a-stream }

"**Streaming**" data means that your app will start sending data items to the client without waiting for the entire sequence of items to be ready.

So, it will send the first item, the client will receive and start processing it, and you might still be producing the next item.

```mermaid

This module enables [Zstandard (zstd)][1] response compression in addition to Gzip, as long as
the `Accept-Encoding` header is not otherwise set. Web servers must be configured to return zstd
responses.

Note that zstd is not used for sending requests.

```java
OkHttpClient client = new OkHttpClient.Builder()
  .addInterceptor(CompressionInterceptor(Zstd, Gzip))
  .build();
```

```kotlin
implementation("com.squareup.okhttp3:okhttp-zstd:5.3.0")

 * limitations under the License.
 */
package mockwebserver3

import okio.Socket

/**
 * Handles a call's request and response streams directly. Use this instead of [MockResponseBody] to
 * begin sending response data before all request data has been received.
 *
 * See [okhttp3.RequestBody.isDuplex].
 */
public interface SocketHandler {
  public fun handle(socket: Socket)

## Reporting a Vulnerability

If you think you found a vulnerability, and even if you are not sure about it, please report it right away by sending an email to: ******@****.***. Please try to be as explicit as possible, describing all the steps and example code to reproduce the security issue.

For change proposals, see [Proposing Changes To Go](https://go.dev/s/proposal-process).

## Contributing code

Please read the [Contribution Guidelines](https://golang.org/doc/contribute.html) before sending patches.

Unless otherwise noted, the Go source files are distributed under

    }
    body.awaitSuccess()
    assertThat(log.take()!!)
      .contains("StreamResetException: stream was reset: CANCEL")
  }

  /**
   * We delay sending the last byte of the request body 1500 ms. The 1000 ms read timeout should
   * only elapse 1000 ms after the request body is sent.
   */
  @Test
  fun headersReadTimeoutDoesNotStartUntilLastRequestBodyByteFire() {

Contributing
============

If you would like to contribute code to OkHttp you can do so through GitHub by
forking the repository and sending a pull request.

When submitting code, please make every effort to follow existing conventions
and style in order to keep the code as readable as possible. Please also make
sure your code compiles by running `./gradlew check`. Checkstyle failures
during compilation indicate errors in your style and can be viewed in the

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 { #more-info }

/// note | Technical Details