Remove unnecessary tests

pkg/analysis_server/test/search/element_references_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.
 
 import 'dart:async';
 
 import 'package:analysis_server/protocol/protocol.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart';
-import 'package:analysis_server/src/services/index/index.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'abstract_search_domain.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ElementReferencesTest);
-    defineReflectiveTests(_NoSearchEngine);
   });
 }
 
 @reflectiveTest
 class ElementReferencesTest extends AbstractSearchDomainTest {
   Element searchElement;
 
   void assertHasRef(SearchResultKind kind, String search, bool isPotential) {
     assertHasResult(kind, search);
     expect(result.isPotential, isPotential);
@@ skipping 636 matching lines @@
   T m() => null;
 }
 ''');
     await findElementReferences('T> {', false);
     expect(searchElement.kind, ElementKind.TYPE_PARAMETER);
     expect(results, hasLength(2));
     assertHasResult(SearchResultKind.REFERENCE, 'T f;');
     assertHasResult(SearchResultKind.REFERENCE, 'T m()');
   }
 }
-
-@reflectiveTest
-class _NoSearchEngine extends AbstractSearchDomainTest {
-  @override
-  Index createIndex() {
-    return null;
-  }
-
-  test_requestError_noSearchEngine() async {
-    addTestFile('''
-main() {
-  var vvv = 1;
-  print(vvv);
-}
-''');
-    Request request = new SearchFindElementReferencesParams(testFile, 0, false)
-        .toRequest('0');
-    Response response = await waitResponse(request);
-    expect(response.error, isNotNull);
-    expect(response.error.code, RequestErrorCode.NO_INDEX_GENERATED);
-  }
-}