Eliminate nondeterminism from analysis server unit tests.

pkg/analysis_server/test/mocks.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library mocks;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:analyzer/src/generated/engine.dart';
@@ skipping 13 matching lines @@
   // Verify the directory exists
   Directory sdkDir = new Directory.fromUri(sdkUri);
   if (!sdkDir.existsSync()) {
     throw 'Specified Dart SDK does not exist: $sdkDir';
   }
 
   return sdkDir.path;
 }
 
 /**
+ * Returns a [Future] that completes after pumping the event queue [times]
+ * times. By default, this should pump the event queue enough times to allow
+ * any code to run, as long as it's not waiting on some external event.
+ */
+Future pumpEventQueue([int times = 20]) {
+  if (times == 0) return new Future.value();
+  // We use a delayed future to allow microtask events to finish. The
+  // Future.value or Future() constructors use scheduleMicrotask themselves and
+  // would therefore not wait for microtask callbacks that are scheduled after
+  // invoking this method.
+  return new Future.delayed(Duration.ZERO, () => pumpEventQueue(times - 1));
+}
+
+/**
  * A mock [WebSocket] for testing.
  */
 class MockSocket<T> implements WebSocket {
   StreamController controller = new StreamController();
   MockSocket twin;
   Stream stream;
 
   factory MockSocket.pair() {
     MockSocket socket1 = new MockSocket();
     MockSocket socket2 = new MockSocket();
@@ skipping 18 matching lines @@
   StreamSubscription<T> listen(void onData(T event),
                      { Function onError, void onDone(), bool cancelOnError}) =>
     stream.listen(onData, onError: onError, onDone: onDone,
         cancelOnError: cancelOnError);
 
   Stream<T> where(bool test(T)) => stream.where(test);
 
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
+class NoResponseException implements Exception {
+  /** The request that was not responded to. */

[Brian Wilkerson, 2014/04/21 14:18:05]

I don't know for sure, but I suspect that this should either be formatted as
  /**
   * The request...
   */
or
  /// The request...

+  final Request request;
+
+  NoResponseException(this.request);
+
+  String toString() {
+    return "NoResponseException after request ${request.toJson()}";
+  }
+}
+
 /**
  * A mock [ServerCommunicationChannel] for testing [AnalysisServer].
  */
 class MockServerChannel implements ServerCommunicationChannel {
   StreamController<Request> requestController = new StreamController<Request>();
   StreamController<Response> responseController = new StreamController<Response>();
   StreamController<Notification> notificationController = new StreamController<Notification>();
 
   List<Response> responsesReceived = [];
   List<Notification> notificationsReceived = [];
@@ skipping 11 matching lines @@
     notificationsReceived.add(notification);
     // Wrap send notification in future to simulate websocket
     new Future(() => notificationController.add(notification));
   }
 
   /// Simulate request/response pair
   Future<Response> sendRequest(Request request) {
     var id = request.id;
     // Wrap send request in future to simulate websocket
     new Future(() => requestController.add(request));
-    return responseController.stream.firstWhere((response) => response.id == id);
+    pumpEventQueue().then((_) => responseController.addError(
+        new NoResponseException(request)));
+    return responseController.stream.firstWhere((response) => response.id == id
+        );
   }
 
   @override
   void sendResponse(Response response) {
     responsesReceived.add(response);
     // Wrap send response in future to simulate websocket
     new Future(() => responseController.add(response));
   }
 
   void expectMsgCount({responseCount: 0, notificationCount: 0}) {
     expect(responsesReceived, hasLength(responseCount));
     expect(notificationsReceived, hasLength(notificationCount));
   }
 }