Add test for filling out missing websocket.disconnect code

tests/test_websockets.py

@@ -559,3 +559,22 @@ async def app(scope, receive, send):
     with pytest.raises(RuntimeError):
         with client.websocket_connect("/") as websocket:
             websocket.send({"type": "websocket.connect"})
+
+
+def test_send_disconnect_no_code(test_client_factory):
+    close_msg: Message = {}
+
+    async def app(scope: Scope, receive: Receive, send: Send) -> None:
+        nonlocal close_msg
+        websocket = WebSocket(scope, receive=receive, send=send)
+        await websocket.accept()
+        close_msg = await websocket.receive()
+
+    client = test_client_factory(app)
+    with client.websocket_connect("/") as websocket:
+        websocket.send({"type": "websocket.disconnect"})
+
+    assert close_msg == {
+        "type": "websocket.disconnect",
+        "code": status.WS_1005_NO_STATUS_RCVD,
+    }