call dispose so completion manager can cancel pending operations

pkg/analysis_server/test/domain_completion_test.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 test.domain.completion;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/channel/channel.dart';
@@ skipping 67 matching lines @@
     completionDomain = null;
   }
 
   /**
    * Assert different managers are used for different sources
    */
   test_2_requests_different_sources() {
     expect(completionDomain.manager, isNull);
     sendRequest(testFile);
     expect(completionDomain.manager, isNotNull);
-    CompletionManager expectedManager = completionDomain.manager;
+    MockCompletionManager expectedManager = completionDomain.manager;
+    expect(expectedManager.disposeCallCount, 0);
     expect(completionDomain.mockContext.mockStream.listenCount, 1);
     expect(completionDomain.mockContext.mockStream.cancelCount, 0);
     return pumpEventQueue().then((_) {
       expect(completionDomain.manager, expectedManager);
       expect(completionDomain.mockManager.computeCallCount, 1);
       sendRequest(testFile2);
       expect(completionDomain.manager, isNotNull);
       expect(completionDomain.manager, isNot(expectedManager));
+      expect(expectedManager.disposeCallCount, 1);
       expectedManager = completionDomain.manager;
       expect(completionDomain.mockContext.mockStream.listenCount, 2);
       expect(completionDomain.mockContext.mockStream.cancelCount, 1);
       return pumpEventQueue();
     }).then((_) {
       expect(completionDomain.manager, expectedManager);
       expect(completionDomain.mockContext.mockStream.listenCount, 2);
       expect(completionDomain.mockContext.mockStream.cancelCount, 1);
       expect(completionDomain.mockManager.computeCallCount, 1);
     });
@@ skipping 326 matching lines @@
 class MockCache extends CompletionCache {
   MockCache(AnalysisContext context, Source source) : super(context, source);
 }
 
 class MockCompletionManager implements CompletionManager {
   final AnalysisContext context;
   final Source source;
   final SearchEngine searchEngine;
   StreamController<CompletionResult> controller;
   int computeCallCount = 0;
+  int disposeCallCount = 0;
 
   MockCompletionManager(this.context, this.source, this.searchEngine);
 
   @override
   Future<bool> computeCache() {
     return new Future.value(true);
   }
 
   @override
   void computeSuggestions(CompletionRequest request) {
     ++computeCallCount;
     CompletionResult result = new CompletionResult(0, 0, [], true);
     controller.add(result);
   }
 
   @override
+  void dispose() {
+    ++disposeCallCount;
+  }
+
+  @override
   Stream<CompletionResult> results(CompletionRequest request) {
     controller = new StreamController<CompletionResult>(onListen: () {
       scheduleMicrotask(() {
         computeSuggestions(request);
       });
     });
     return controller.stream;
   }
 }
 
@@ skipping 89 matching lines @@
 
   void contextsChangedRaw(ContextsChangedEvent newEvent) {
     super.contextsChanged(newEvent);
   }
 
   CompletionManager createCompletionManager(AnalysisContext context,
       Source source, SearchEngine searchEngine) {
     return new MockCompletionManager(mockContext, source, searchEngine);
   }
 }