Allow completions to wait for analysis without requiring a busy wait loop.

pkg/analysis_server/test/services/completion/completion_computer_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.services.completion.suggestion;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
@@ skipping 32 matching lines @@
 class DartCompletionManagerTest extends AbstractSingleUnitTest {
   Index index;
   SearchEngineImpl searchEngine;
   Source source;
   CompletionPerformance perf;
   DartCompletionManager manager;
   MockCompletionComputer computer1;
   MockCompletionComputer computer2;
   CompletionSuggestion suggestion1;
   CompletionSuggestion suggestion2;
+  bool _continuePerformingAnalysis = true;
 
   void resolveLibrary() {
     context.resolveCompilationUnit(
         source,
         context.computeLibraryElement(source));
   }
 
   @override
   void setUp() {
     super.setUp();
@@ skipping 11 matching lines @@
         false,
         false);
     suggestion2 = new CompletionSuggestion(
         CompletionSuggestionKind.IDENTIFIER,
         CompletionRelevance.DEFAULT,
         "suggestion2",
         2,
         2,
         false,
         false);
+    new Future(_performAnalysis);
+  }
+
+  @override
+  void tearDown() {
+    _continuePerformingAnalysis = false;
   }
 
   test_compute_fastAndFull() {
     computer1 = new MockCompletionComputer(suggestion1, null);
     computer2 = new MockCompletionComputer(null, suggestion2);
     manager.computers = [computer1, computer2];
     int count = 0;
     bool done = false;
     CompletionRequest completionRequest = new CompletionRequest(0, perf);
     manager.results(completionRequest).listen((CompletionResult r) {
@@ skipping 47 matching lines @@
           fail('unexpected');
       }
     }, onDone: () {
       done = true;
       expect(count, equals(1));
     });
     return pumpEventQueue().then((_) {
       expect(done, isTrue);
     });
   }
+
+  void _performAnalysis() {
+    if (!_continuePerformingAnalysis) {
+      return;
+    }
+    context.performAnalysisTask();
+    new Future(_performAnalysis);
+  }
 }
 
 class MockCompletionComputer extends DartCompletionComputer {
   final CompletionSuggestion fastSuggestion;
   final CompletionSuggestion fullSuggestion;
   int fastCount = 0;
   int fullCount = 0;
   DartCompletionRequest request;
 
   MockCompletionComputer(this.fastSuggestion, this.fullSuggestion);
@@ skipping 26 matching lines @@
   @override
   Future<bool> computeFull(DartCompletionRequest request) {
     this.request = request;
     fullCount++;
     if (fullSuggestion != null) {
       request.suggestions.add(fullSuggestion);
     }
     return new Future.value(fullSuggestion != null);
   }
 }