Return RequestErrorCode.NO_INDEX_GENERATED for search/refactoring requests.

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.
 
 library test.search.element_references;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_server/src/services/index/index.dart';
 import 'package:unittest/unittest.dart';
 
 import '../reflective_tests.dart';
 import 'abstract_search_domain.dart';
 
 
 main() {
   groupSep = ' | ';
   runReflectiveTests(ElementReferencesTest);
+  runReflectiveTests(_NoSearchEngine);
 }
 
 
 @reflectiveTest
 class ElementReferencesTest extends AbstractSearchDomainTest {
   Element searchElement;
 
   void assertHasRef(SearchResultKind kind, String search, bool isPotential) {
     assertHasResult(kind, search);
     expect(result.isPotential, isPotential);
@@ skipping 668 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);
+  }
+}