denote completion offset using special character

pkg/analysis_server/test/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/constants.dart';
 import 'package:analysis_server/src/domain_completion.dart';
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_services/index/index.dart' show Index;
 import 'package:analysis_services/index/local_memory_index.dart';
 import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
 
 import 'analysis_abstract.dart';
 
 main() {
   group('completion', () {
     runReflectiveTests(CompletionTest);
   });
 }
 
 @ReflectiveTestCase()
 class CompletionTest extends AbstractAnalysisTest {
   String completionId;
+  int completionOffset;
   List<CompletionSuggestion> suggestions = [];
   bool suggestionsDone = false;
 
+  String addTestFile(String content) {
+    completionOffset = content.indexOf('^');
+    expect(completionOffset, isNot(equals(-1)), reason: 'missing ^');
+    int nextOffset = content.indexOf('^', completionOffset + 1);
+    expect(nextOffset, equals(-1), reason: 'too many ^');
+    return super.addTestFile(
+        content.substring(0, completionOffset)
+        + content.substring(completionOffset + 1));
+  }
+
   void assertHasResult(String completion) {
     var cs = suggestions.firstWhere((cs) => cs.completion == completion, orElse: () {
       var completions = suggestions.map((s) => s.completion).toList();
       fail('expected "$completion" but found\n $completions');
     });
   }
 
   void assertValidId(String id) {
     expect(id, isNotNull);
     expect(id.isNotEmpty, isTrue);
   }
 
   @override
   Index createIndex() {
     return createLocalMemoryIndex();
   }
 
-  Future getSuggestions(String pattern, int offsetFromPatternStart) {
+  Future getSuggestions() {
     return waitForTasksFinished().then((_) {
-      int offset = testCode.indexOf(pattern) + offsetFromPatternStart;
       Request request = new Request('0', COMPLETION_GET_SUGGESTIONS);
       request.setParameter(FILE, testFile);
-      request.setParameter(OFFSET, offset);
+      request.setParameter(OFFSET, completionOffset);
       Response response = handleSuccessfulRequest(request);
       completionId = response.getResult(ID);
       assertValidId(completionId);
       return waitForSuggestions();
     });
   }
 
   void processNotification(Notification notification) {
     if (notification.event == COMPLETION_RESULTS) {
       String id = notification.getParameter(ID);
@@ skipping 20 matching lines @@
   Future waitForSuggestions() {
     if (suggestionsDone) {
       return new Future.value();
     }
     return new Future.delayed(Duration.ZERO, waitForSuggestions);
   }
 
   test_suggestions() {
     addTestFile('''
       import 'dart:html';
-      main() {}
+      main() {^}
     ''');
-    return getSuggestions('}', 0).then((_) {
+    return getSuggestions().then((_) {
       assertHasResult('Object');
       assertHasResult('HtmlElement');
     });
   }
 }