Display a pause screen in a paused browser.

lib/src/runner/browser/browser_manager.dart

 // Copyright (c) 2015, 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 test.runner.browser.browser_manager;
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'package:http_parser/http_parser.dart';
 import 'package:pool/pool.dart';
 
 import '../../backend/metadata.dart';
 import '../../backend/test_platform.dart';
+import '../../util/cancelable_future.dart';
 import '../../util/multi_channel.dart';
 import '../../util/remote_exception.dart';
 import '../../util/stack_trace_mapper.dart';
 import '../../utils.dart';
 import '../environment.dart';
 import '../load_exception.dart';
 import '../runner_suite.dart';
 import 'iframe_test.dart';
 
 /// A class that manages the connection to a single running browser.
@@ skipping 20 matching lines @@
 
   /// The ID of the next suite to be loaded.
   ///
   /// This is used to ensure that the suites can be referred to consistently
   /// across the client and server.
   int _suiteId = 0;
 
   /// Whether the channel to the browser has closed.
   bool _closed = false;
 
+  /// The completer for [_BrowserEnvironment.displayPause].
+  ///
+  /// This will be `null` as long as the browser isn't displaying a pause
+  /// screen.
+  CancelableCompleter _pauseCompleter;
+
   /// The environment to attach to each suite.
   _BrowserEnvironment _environment;
 
   /// Creates a new BrowserManager that communicates with [browser] over
   /// [webSocket].
   BrowserManager(this.browser, CompatibleWebSocket webSocket)
       : _channel = new MultiChannel(
           webSocket.map(JSON.decode),
           mapSink(webSocket, JSON.encode)) {
     _environment = new _BrowserEnvironment(this);
-    _channel.stream.listen(null, onDone: () => _closed = true);
+    _channel.stream.listen(_onMessage, onDone: _onDone);
   }
 
   /// Tells the browser the load a test suite from the URL [url].
   ///
   /// [url] should be an HTML page with a reference to the JS-compiled test
   /// suite. [path] is the path of the original test suite file, which is used
   /// for reporting. [metadata] is the parsed metadata for the test suite.
   ///
   /// If [mapper] is passed, it's used to map stack traces for errors coming
   /// from this test suite.
@@ skipping 70 matching lines @@
     }
 
     return new RunnerSuite(_environment, response["tests"].map((test) {
       var testMetadata = new Metadata.deserialize(test['metadata']);
       var testChannel = suiteChannel.virtualChannel(test['channel']);
       return new IframeTest(test['name'], testMetadata, testChannel,
           mapper: mapper);
     }), platform: browser, metadata: metadata, path: path,
         onClose: () => closeIframe());
   }
+
+  /// An implementation of [Environment.displayPause].
+  CancelableFuture _displayPause() {
+    if (_pauseCompleter != null) return _pauseCompleter.future;
+
+    _pauseCompleter = new CancelableCompleter(() {
+      _channel.sink.add({"command": "resume"});
+      _pauseCompleter = null;
+    });
+
+    _channel.sink.add({"command": "displayPause"});
+    return _pauseCompleter.future.whenComplete(() {
+      _pauseCompleter = null;
+    });
+  }
+
+  /// The callback for handling messages received from the host page.
+  void _onMessage(Map message) {
+    assert(message["command"] == "resume");
+    if (_pauseCompleter == null) return;
+    _pauseCompleter.complete();
+  }
+
+  /// The callback called when the WebSocket is closed.
+  void _onDone() {
+    _closed = true;
+    if (_pauseCompleter != null) _pauseCompleter.complete();
+    _pauseCompleter = null;
+  }
 }
 
 /// An implementation of [Environment] for the browser.
 ///
 /// All methods forward directly to [BrowserManager].
 class _BrowserEnvironment implements Environment {
   final BrowserManager _manager;
 
   _BrowserEnvironment(this._manager);
+
+  CancelableFuture displayPause() => _manager._displayPause();
 }