Update COMPILATION_UNIT_CONSTANTS after incremental elements building.

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/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/element/element.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';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_collection.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/src/task/html.dart';
 import 'package:analyzer/task/dart.dart';
@@ skipping 3354 matching lines @@
       expect(analysisCache.getValue(target, RESOLVED_UNIT1), same(unitA));
       expect(unitA.element, same(unitElementA));
       expect(unitElementA.library, same(libraryElementA));
     }
     // Analyze.
     _performPendingAnalysisTasks();
     expect(context.getErrors(a).errors, hasLength(0));
     expect(context.getErrors(b).errors, hasLength(0));
   }
 
+  void test_sequence_unitConstants() {
+    Source a = addSource(
+        '/a.dart',
+        r'''
+const A = 1;
+const B = 2;
+const C = 3;
+''');
+    _performPendingAnalysisTasks();
+    LibrarySpecificUnit unitA = new LibrarySpecificUnit(a, a);
+    expect(context.getResult(unitA, COMPILATION_UNIT_CONSTANTS), hasLength(3));
+    // Update and
+    context.setContents(
+        a,
+        r'''
+const A = 1;
+const B = 2;
+const D = 4;
+main() {
+  const V = 42;
+}
+''');
+    List<ConstantEvaluationTarget> constants =
+        context.getResult(unitA, COMPILATION_UNIT_CONSTANTS);
+    expect(constants, hasLength(4));
+    // Perform analysis, compute constant values.
+    _performPendingAnalysisTasks();
+    // Validate const variable values.
+    Map<String, ConstVariableElement> constVariables =
+        <String, ConstVariableElement>{};
+    constants.forEach((c) {
+      if (c is ConstVariableElement) {
+        constVariables[c.name] = c;
+      }
+    });
+    expect(constVariables['A'].evaluationResult.value.toIntValue(), 1);
+    expect(constVariables['B'].evaluationResult.value.toIntValue(), 2);
+    expect(constVariables['D'].evaluationResult.value.toIntValue(), 4);
+    expect(constVariables['V'].evaluationResult.value.toIntValue(), 42);
+  }
+
   void test_sequence_useAnyResolvedUnit() {
     Source a = addSource(
         '/a.dart',
         r'''
 class A {}
 class B {}
 ''');
     Source b = addSource(
         '/b.dart',
         r'''
@@ skipping 572 matching lines @@
    * Initialize the visitor.
    */
   _ElementGatherer();
 
   @override
   void visitElement(Element element) {
     elements[element] = element;
     super.visitElement(element);
   }
 }