# Testing WebSockets { #testing-websockets }

You can use the same `TestClient` to test WebSockets.

For this, you use the `TestClient` in a `with` statement, connecting to the WebSocket:

{* ../../docs_src/app_testing/tutorial002_py39.py hl[27:31] *}

/// note

For more details, check Starlette's documentation for <a href="https://www.starlette.dev/testclient/#testing-websocket-sessions" class="external-link" target="_blank">testing WebSockets</a>.

    "@local_config_cuda//cuda:curand + "\
    "@local_config_cuda//cuda:cusolver + "\
    "@local_config_tensorrt//:tensorrt)" --keep_going > $BATS_TEST_TMPDIR/out

  cat <<EOF
There was a path found connecting //tensorflow/tools/pip_package:wheel
to a banned CUDA dependency. Here's the output from bazel query:
EOF
  cat $BATS_TEST_TMPDIR/out
  [[ ! -s $BATS_TEST_TMPDIR/out ]]
}

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:

    in logs. For best security, don't put sensitive information in query parameters.

 *  New: `ConnectionPool.setPolicy()` configures a minimum connection pool size for a target
    address. Use this to proactively open HTTP connections.

    Connections opened to fulfill this policy are subject to the connection pool's
    `keepAliveDuration` but do not count against the pool-wide `maxIdleConnections` limit.

If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.
These kinds of changes are unavoidable and
[permitted by the Go 1 compatibility rules](/doc/go1compat).
Even so, Go provides a mechanism called GODEBUG to

            } else {
                logger.warn("Invalid index config name: configName={}", configName);
            }
        });
    }

    /**
     * Creates an HTTP client for connecting to the search engine.
     *
     * @param fessConfig the Fess configuration
     * @param host       the search engine host address
     * @return the configured HTTP client
     */

 * </p>
 */
public class Handler extends URLStreamHandler {

    /**
     * Constructs a new Handler.
     */
    public Handler() {
        // Default constructor
    }

    /**
     * Opens a connection to the GCS URL.
     *
     * @param u The URL to open a connection to
     * @return A new GcsURLConnection instance

 * The {@link S3URLConnection} class handles the actual connection and data retrieval from the S3 service.
 * </p>
 */
public class Handler extends URLStreamHandler {

    /**
     * Constructs a new Handler.
     */
    public Handler() {
        // Default constructor
    }

    /**
     * Opens a connection to the S3 URL.
     *
     * @param u The URL to open a connection to
     * @return A new S3URLConnection instance

<img src="/img/tutorial/websockets/image03.png">

You can send (and receive) many messages:

<img src="/img/tutorial/websockets/image04.png">

And all of them will use the same WebSocket connection.

## Using `Depends` and others { #using-depends-and-others }

In WebSocket endpoints you can import from `fastapi` and use:

* `Depends`
* `Security`
* `Cookie`
* `Header`
* `Path`

def test_websocket_handle_disconnection(client: TestClient):
    with (
        client.websocket_connect("/ws/1234") as connection,
        client.websocket_connect("/ws/5678") as connection_two,
    ):
        connection.send_text("Hello from 1234")
        data1 = connection.receive_text()
        assert data1 == "You wrote: Hello from 1234"
        data2 = connection_two.receive_text()