Always update 'modificationTime' in _sourceChanged().

pkg/analyzer/test/src/context/context_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 analyzer.test.src.context.context_test;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/dart/element/visitor.dart';
+import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/src/cancelable_future.dart';
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/context/context.dart';
 import 'package:analyzer/src/dart/scanner/scanner.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
@@ skipping 248 matching lines @@
     changeSet2.addedSource(source2);
     changeSet2.changedRange(source, 'library test;', 0, 0, 13);
     context.applyChanges(changeSet2);
     return pumpEventQueue().then((_) {
       listener.assertEvent(wereSourcesAdded: true);
       listener.assertEvent(wereSourcesAdded: true, changedSources: [source]);
       listener.assertNoMoreEvents();
     });
   }
 
+  void test_applyChanges_changedSource_updateModificationTime() {
+    String path = '/test.dart';
+    File file = resourceProvider.newFile(path, 'var V = 1;');
+    Source source = file.createSource();
+    context.applyChanges(new ChangeSet()..addedSource(source));
+    // Analyze all.
+    _analyzeAll_assertFinished();
+    expect(context.analysisCache.getState(source, RESOLVED_UNIT),
+        CacheState.INVALID);
+    // Update the file and notify the context about the change.
+    resourceProvider.updateFile(path, 'var V = 2;');
+    context.applyChanges(new ChangeSet()..changedSource(source));
+    // The analysis results are invalidated.
+    // We have seen the new contents, so 'modificationTime' is also updated.
+    expect(context.analysisCache.getState(source, RESOLVED_UNIT),
+        CacheState.INVALID);
+    expect(
+        context.getCacheEntry(source).modificationTime, file.modificationStamp);
+  }
+
   void test_applyChanges_empty() {
     context.applyChanges(new ChangeSet());
     expect(context.performAnalysisTask().changeNotices, isNull);
   }
 
   void test_applyChanges_overriddenSource() {
     String content = "library test;";
     Source source = addSource("/test.dart", content);
     context.setContents(source, content);
     context.computeErrors(source);
@@ skipping 1823 matching lines @@
     TestSource source = _addSourceWithException2("/test.dart", "library test;");
     source.generateExceptionOnRead = false;
     _analyzeAll_assertFinished();
     expect(source.readCount, 2);
     _changeSource(source, "");
     source.generateExceptionOnRead = true;
     _analyzeAll_assertFinished();
     if (context.analysisOptions.finerGrainedInvalidation) {
       expect(source.readCount, 7);
     } else {
-      expect(source.readCount, 4);
+      expect(source.readCount, 5);
     }
   }
 
   void test_performAnalysisTask_missingPart() {
     Source source =
         addSource("/test.dart", "library lib; part 'no-such-file.dart';");
     _analyzeAll_assertFinished();
     expect(context.getLibraryElement(source), isNotNull,
         reason: "performAnalysisTask failed to compute an element model");
   }
@@ skipping 1839 matching lines @@
    * Initialize the visitor.
    */
   _ElementGatherer();
 
   @override
   void visitElement(Element element) {
     elements[element] = element;
     super.visitElement(element);
   }
 }