Get memento objects from tasks, remember in cache and pass back to tasks.

pkg/analyzer/test/src/context/cache_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.src.task.driver_test;
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, CacheState, RetentionPriority;
@@ skipping 190 matching lines @@
     expect(entry.getState(result), CacheState.INVALID);
   }
 
   test_getValue() {
     String defaultValue = 'value';
     ResultDescriptor result = new ResultDescriptor('test', defaultValue);
     CacheEntry entry = new CacheEntry();
     expect(entry.getValue(result), defaultValue);
   }
 
+  test_getMemento_noResult() {
+    String defaultValue = 'value';
+    ResultDescriptor result = new ResultDescriptor('test', defaultValue);
+    CacheEntry entry = new CacheEntry();
+    expect(entry.getMemento(result), null);
+  }
+
   test_hasAstStructure_false() {
     CacheEntry entry = new CacheEntry();
     expect(entry.hasAstStructure, false);
   }
 
   test_hasAstStructure_true() {
     ResultDescriptor result = new ResultDescriptor('test', null);
     CacheEntry entry = new CacheEntry();
     entry.setValue(result, new NullLiteral(null), TargetedResult.EMPTY_LIST);
     expect(entry.hasAstStructure, true);
@@ skipping 139 matching lines @@
     // set IN_PROCESS
     entry.setState(result, CacheState.IN_PROCESS);
     expect(entry.getState(result), CacheState.IN_PROCESS);
     expect(entry.getValue(result), 10);
   }
 
   test_setState_invalid() {
     ResultDescriptor result = new ResultDescriptor('test', 1);
     CacheEntry entry = new CacheEntry();
     // set VALID
-    entry.setValue(result, 10, TargetedResult.EMPTY_LIST);
+    String memento = 'main() {}';
+    entry.setValue(result, 10, TargetedResult.EMPTY_LIST, memento);
     expect(entry.getState(result), CacheState.VALID);
     expect(entry.getValue(result), 10);
     // set INVALID
     entry.setState(result, CacheState.INVALID);
     expect(entry.getState(result), CacheState.INVALID);
     expect(entry.getValue(result), 1);
+    expect(entry.getMemento(result), memento);
   }
 
   test_setState_invalid_invalidateDependent() {
     AnalysisCache cache = createCache();
     AnalysisTarget target = new TestSource();
     CacheEntry entry = new CacheEntry();
     cache.put(target, entry);
     ResultDescriptor result1 = new ResultDescriptor('result1', -1);
     ResultDescriptor result2 = new ResultDescriptor('result2', -2);
     ResultDescriptor result3 = new ResultDescriptor('result3', -3);
@@ skipping 23 matching lines @@
     expect(entry.getValue(result4), 444);
   }
 
   test_setState_valid() {
     ResultDescriptor result = new ResultDescriptor('test', null);
     CacheEntry entry = new CacheEntry();
     expect(() => entry.setState(result, CacheState.VALID), throwsArgumentError);
   }
 
   test_setValue() {
+    ResultDescriptor result = new ResultDescriptor('test', null);
     String value = 'value';
-    ResultDescriptor result = new ResultDescriptor('test', null);
+    String memento = 'main() {}';
     CacheEntry entry = new CacheEntry();
-    entry.setValue(result, value, TargetedResult.EMPTY_LIST);
+    entry.setValue(result, value, TargetedResult.EMPTY_LIST, memento);
     expect(entry.getState(result), CacheState.VALID);
     expect(entry.getValue(result), value);
+    expect(entry.getMemento(result), memento);
   }
 
   test_setValue_invalidateDependent() {
     AnalysisCache cache = createCache();
     AnalysisTarget target = new TestSource();
     CacheEntry entry = new CacheEntry();
     cache.put(target, entry);
     ResultDescriptor result1 = new ResultDescriptor('result1', -1);
     ResultDescriptor result2 = new ResultDescriptor('result2', -2);
     ResultDescriptor result3 = new ResultDescriptor('result3', -3);
@@ skipping 203 matching lines @@
     return new UniversalCachePartition(null, 8, policy);
   }
 
   void test_contains() {
     UniversalCachePartition partition =
         new UniversalCachePartition(null, 8, null);
     TestSource source = new TestSource();
     expect(partition.contains(source), isTrue);
   }
 }