MockWebSocketServer.md

Testing/Mocks: Mock WebSocket Server

In order to mock out a WebSocket, you have to provide and control a mock WebSocket server. To do this, you construct an instance of MockWebSocketServer and either provide it when setting up an expectation, or return it from a handler.

Just like an actual server, a MockWebSocketServer instance can serve multiple transport.WebSocket instances.

import 'package:w_transport/mock.dart';

...

var mockWebSocketServer = new MockWebSocketServer();

A stream of connections is available on the mock WebSocket server. Listening to this stream allows you to setup listeners for each connected client so that incoming data can be read and data can be sent to the client.

var mockWebSocketServer = new MockWebSocketServer();
mockWebSocketServer.onClientConnected.listen((MockWebSocketConnection connection) {
  // Echo any message from the client
  connection.onData((data) {
    connection.send(data);
  });
});

There is a Future done field available on the connection that allows you to listen for when it has closed.

var mockWebSocketServer = new MockWebSocketServer();
mockWebSocketServer.onClientConnected.listen((MockWebSocketConnection connection) {
  connection.done.then((_) { ... });
});

Additionally, you can close the connection at any time.

var mockWebSocketServer = new MockWebSocketServer();
mockWebSocketServer.onClientConnected.listen((MockWebSocketConnection connection) {
  ...
  
  await connection.close(4000, 'Mock server closed connection.');
});

Finally, you may choose to shut down the entire mock server at any time, which will terminate any active connections.

var mockWebSocketServer = new MockWebSocketServer();
mockWebSocketServer.onClientConnected.listen(
    (MockWebSocketConnection connection) { ... });

...

await mockWebSocketServer.shutDown();