refactor code completion to allow for multiple suggestion computers

pkg/analysis_services/test/completion/top_level_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.toplevel;
 
 import 'package:analysis_services/completion/completion_suggestion.dart';
-import 'package:analysis_services/completion/top_level_computer.dart';
-import 'package:analysis_services/index/index.dart';
-import 'package:analysis_services/index/local_memory_index.dart';
-import 'package:analysis_services/src/search/search_engine.dart';
-import 'package:analysis_testing/abstract_single_unit.dart';
+import 'package:analysis_services/src/completion/top_level_computer.dart';
 import 'package:analysis_testing/reflective_tests.dart';
 import 'package:unittest/unittest.dart';
-import 'dart:async';
+
+import 'completion_test_util.dart';
 
 main() {
   groupSep = ' | ';
   runReflectiveTests(TopLevelComputerTest);
 }
 
 @ReflectiveTestCase()
-class TopLevelComputerTest extends AbstractSingleUnitTest {
-  Index index;
-  SearchEngineImpl searchEngine;
-  TopLevelComputer computer;
-  List<CompletionSuggestion> suggestions;
+class TopLevelComputerTest extends AbstractCompletionTest {
 
   test_class() {
     addTestUnit('class B {boolean v;}');
     return compute().then((_) {
       assertHasResult(CompletionSuggestionKind.CLASS, 'B');
       assertNoResult('v');
     });
   }
 
-  void addTestUnit(String code) {
-    resolveTestUnit(code);
-    index.indexUnit(context, testUnit);
-  }
-
-  void assertHasResult(CompletionSuggestionKind kind, String completion,
-      [CompletionRelevance relevance = CompletionRelevance.DEFAULT,
-      bool isDeprecated = false, bool isPotential = false]) {
-    var cs = suggestions.firstWhere((cs) => cs.completion == completion, orElse: () {
-      var completions = suggestions.map((s) => s.completion).toList();
-      fail('expected "$completion" but found\n $completions');
-    });
-    expect(cs.kind, equals(kind));
-    expect(cs.relevance, equals(relevance));
-    expect(cs.selectionOffset, equals(completion.length));
-    expect(cs.selectionLength, equals(0));
-    expect(cs.isDeprecated, equals(isDeprecated));
-    expect(cs.isPotential, equals(isPotential));
-  }
-
-  void assertNoResult(String completion) {
-    if (suggestions.any((cs) => cs.completion == completion)) {
-      fail('did not expect completion: $completion');
-    }
-  }
-
-  Future compute() {
-    return computer.compute().then((List<CompletionSuggestion> results) {
-      this.suggestions = results;
-    });
-  }
-
   @override
   void setUp() {
     super.setUp();
-    index = createLocalMemoryIndex();
-    searchEngine = new SearchEngineImpl(index);
     computer = new TopLevelComputer(searchEngine);
-    verifyNoTestUnitErrors = false;
   }
 }