Reset Source modification stamp to -1 if it does not exist.

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 test.src.context.context_test;
 
 import 'dart:async';
 
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/cancelable_future.dart';
@@ skipping 1754 matching lines @@
         reason: "libA resolved 2");
     expect(_hasAnalysisErrorWithErrorSeverity(context.getErrors(libASource)),
         isTrue,
         reason: "libA has an error");
   }
 
   void test_performAnalysisTask_IOException() {
     TestSource source = _addSourceWithException2("/test.dart", "library test;");
     source.generateExceptionOnRead = false;
     _analyzeAll_assertFinished();
-    expect(source.readCount, 1);
+    expect(source.readCount, 2);

[Brian Wilkerson, 2015/09/23 13:53:38]

I don't understand why this change would cause the source to be read more times.
That seems like a problem.

[scheglov, 2015/09/23 15:11:27]

The scenario is following.

1. We add test.dart as not existing source in _addSourceWithException2(), so its
modificationStamp is -1.

2. GetContentTask attempts to read it (1-st time), fails, uses an empty string.

3. Then in the test we make test.dart existing again, so newly added
validateCacheConsistency() invocation in _analyzeAll_assertFinished() notices
that test.dart CacheEntry.modificationTime(-1) != source.modificationTime(0). It
marks the source as changed.

4. In _sourceChanged() we attempt to read the source again (2-nd time), get an
exception, and set modificationTime to -1.

  Basically we get this change because of adding
context.validateCacheConsistency() invocation.

     _changeSource(source, "");
     source.generateExceptionOnRead = true;
     _analyzeAll_assertFinished();
     if (AnalysisEngine.instance.limitInvalidationInTaskModel) {
+      expect(source.readCount, 7);
+    } else {
       expect(source.readCount, 5);
-    } else {
-      expect(source.readCount, 3);
     }
   }
 
   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 69 matching lines @@
         context.resolveCompilationUnit2(sourceA, sourceA);
     expect(compilationUnit, isNotNull);
     LibraryElement library = compilationUnit.element.library;
     List<LibraryElement> importedLibraries = library.importedLibraries;
     assertNamedElements(importedLibraries, ["dart.core", "libB"]);
     List<LibraryElement> visibleLibraries = library.visibleLibraries;
     assertNamedElements(visibleLibraries,
         ["dart.core", "dart.async", "dart.math", "libA", "libB"]);
   }
 
+  void test_resolveCompilationUnit_library() {
+    Source source = addSource("/lib.dart", "library lib;");
+    LibraryElement library = context.computeLibraryElement(source);
+    CompilationUnit compilationUnit =
+        context.resolveCompilationUnit(source, library);
+    expect(compilationUnit, isNotNull);
+    expect(compilationUnit.element, isNotNull);
+  }
+
 //  void test_resolveCompilationUnit_sourceChangeDuringResolution() {
 //    _context = new _AnalysisContext_sourceChangeDuringResolution();
 //    AnalysisContextFactory.initContextWithCore(_context);
 //    _sourceFactory = _context.sourceFactory;
 //    Source source = _addSource("/lib.dart", "library lib;");
 //    CompilationUnit compilationUnit =
 //        _context.resolveCompilationUnit2(source, source);
 //    expect(compilationUnit, isNotNull);
 //    expect(_context.getLineInfo(source), isNotNull);
 //  }
 
-  void test_resolveCompilationUnit_library() {
-    Source source = addSource("/lib.dart", "library lib;");
-    LibraryElement library = context.computeLibraryElement(source);
-    CompilationUnit compilationUnit =
-        context.resolveCompilationUnit(source, library);
-    expect(compilationUnit, isNotNull);
-    expect(compilationUnit.element, isNotNull);
-  }
-
   void test_resolveCompilationUnit_source() {
     Source source = addSource("/lib.dart", "library lib;");
     CompilationUnit compilationUnit =
         context.resolveCompilationUnit2(source, source);
     expect(compilationUnit, isNotNull);
   }
 
   void test_setAnalysisOptions() {
     AnalysisOptionsImpl options = new AnalysisOptionsImpl();
     options.cacheSize = 42;
@@ skipping 164 matching lines @@
     AnalysisDelta delta = new AnalysisDelta();
     delta.setAnalysisLevel(source, AnalysisLevel.ALL);
     context.applyAnalysisDelta(delta);
     expect(context.sourcesNeedingProcessing, contains(source));
     delta = new AnalysisDelta();
     delta.setAnalysisLevel(source, AnalysisLevel.NONE);
     context.applyAnalysisDelta(delta);
     expect(context.sourcesNeedingProcessing.contains(source), isFalse);
   }
 
+  void test_validateCacheConsistency_deletedSource() {
+    MemoryResourceProvider resourceProvider = new MemoryResourceProvider();
+    var fileA = resourceProvider.newFile('/a.dart', "");
+    var fileB = resourceProvider.newFile('/b.dart', "import 'a.dart';");
+    Source sourceA = fileA.createSource();
+    Source sourceB = fileB.createSource();
+    context.applyChanges(
+        new ChangeSet()..addedSource(sourceA)..addedSource(sourceB));
+    // analyze everything
+    _analyzeAll_assertFinished();
+    // delete a.dart
+    resourceProvider.deleteFile('/a.dart');
+    // analysis should eventually stop
+    _analyzeAll_assertFinished();
+  }
+
   void xtest_performAnalysisTask_stress() {
     int maxCacheSize = 4;
     AnalysisOptionsImpl options =
         new AnalysisOptionsImpl.from(context.analysisOptions);
     options.cacheSize = maxCacheSize;
     context.analysisOptions = options;
     int sourceCount = maxCacheSize + 2;
     List<Source> sources = <Source>[];
     ChangeSet changeSet = new ChangeSet();
     for (int i = 0; i < sourceCount; i++) {
@@ skipping 30 matching lines @@
     return source;
   }
 
   /**
    * Perform analysis tasks up to 512 times and assert that it was enough.
    */
   void _analyzeAll_assertFinished([int maxIterations = 512]) {
     for (int i = 0; i < maxIterations; i++) {
       List<ChangeNotice> notice = context.performAnalysisTask().changeNotices;
       if (notice == null) {
-        return;
+        bool inconsistent = context.validateCacheConsistency();
+        if (!inconsistent) {
+          return;
+        }
       }
     }
     fail("performAnalysisTask failed to terminate after analyzing all sources");
   }
 
   void _changeSource(TestSource source, String contents) {
     source.setContents(contents);
     ChangeSet changeSet = new ChangeSet();
     changeSet.changedSource(source);
     context.applyChanges(changeSet);
@@ skipping 366 matching lines @@
   }
 }
 
 class _AnalysisContextImplTest_test_applyChanges_removeContainer
     implements SourceContainer {
   Source libB;
   _AnalysisContextImplTest_test_applyChanges_removeContainer(this.libB);
   @override
   bool contains(Source source) => source == libB;
 }