Don't remove indexing operations on potential source changes.

pkg/analysis_server/test/analysis/update_content_test.dart

 // Copyright (c) 2015, 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.analysis.updateContent;
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_server/src/services/index/index.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:typed_mock/typed_mock.dart';
 import 'package:unittest/unittest.dart';
 
 import '../analysis_abstract.dart';
 import '../reflective_tests.dart';
 
 
 main() {
   groupSep = ' | ';
   runReflectiveTests(UpdateContentTest);
 }
 
 
+compilationUnitMatcher(String file) {
+  return new _ArgumentMatcher_CompilationUnit(file);
+}
+
+
 @reflectiveTest
 class UpdateContentTest extends AbstractAnalysisTest {
   Map<String, List<AnalysisError>> filesErrors = {};
   int serverErrorCount = 0;
   int navigationCount = 0;
 
+  Index createIndex() {
+    return new _MockIndex();
+  }
+
   @override
   void processNotification(Notification notification) {
     if (notification.event == ANALYSIS_ERRORS) {
       var decoded = new AnalysisErrorsParams.fromNotification(notification);
       filesErrors[decoded.file] = decoded.errors;
     }
     if (notification.event == ANALYSIS_NAVIGATION) {
       navigationCount++;
     }
     if (notification.event == SERVER_ERROR) {
@@ skipping 36 matching lines @@
       server.updateContent(id, {
         testFile: new ChangeContentOverlay([new SourceEdit(8, 3, 'bar')])
       });
       fail('Expected an exception to be thrown');
     } on RequestFailure catch (e) {
       expect(e.response.id, id);
       expect(e.response.error.code, RequestErrorCode.INVALID_OVERLAY_CHANGE);
     }
   }
 
+  test_indexUnitAfterNopChange() async {
+    var testUnitMatcher = compilationUnitMatcher(testFile) as dynamic;
+    createProject();
+    addTestFile('main() { print(1); }');
+    await server.onAnalysisComplete;
+    verify(server.index.indexUnit(anyObject, testUnitMatcher)).times(1);
+    // add an overlay
+    server.updateContent('1', {
+      testFile: new AddContentOverlay('main() { print(2); }')
+    });
+    // Perform a single operation: analysis.
+    // It will schedule an indexing operation.
+    server.performOperation();
+    // Update the file and remove an overlay.
+    resourceProvider.updateFile(testFile, 'main() { print(2); }');
+    server.updateContent('2', {
+      testFile: new RemoveContentOverlay()
+    });
+    // Validate that at the end the unit was indexed.
+    await server.onAnalysisComplete;
+    verify(server.index.indexUnit(anyObject, testUnitMatcher)).times(2);
+  }
+
   test_multiple_contexts() {
     String fooPath = '/project1/foo.dart';
     resourceProvider.newFile(fooPath, '''
 library foo;
 import '../project2/baz.dart';
 main() { f(); }''');
     String barPath = '/project2/bar.dart';
     resourceProvider.newFile(barPath, '''
 library bar;
 import 'baz.dart';
@@ skipping 60 matching lines @@
     filesErrors.clear();
     server.test_flushResolvedUnit(testFile);
     server.updateContent('2', {
       testFile: new ChangeContentOverlay([new SourceEdit(0, 4, 'main')])
     });
     await server.onAnalysisComplete;
     // errors should have been resent
     expect(filesErrors, isNotEmpty);
   }
 }
+
+
+class _ArgumentMatcher_CompilationUnit extends ArgumentMatcher {
+  final String file;
+
+  _ArgumentMatcher_CompilationUnit(this.file);
+
+  @override
+  bool matches(arg) {
+    return arg is CompilationUnit && arg.element.source.fullName == file;
+  }
+}
+
+
+class _MockIndex extends TypedMock implements Index {
+  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}