Correctly recognize non-constant enum children (issue 29306)

pkg/analyzer/test/src/dart/element/element_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.dart.element.element_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 1305 matching lines @@
     }
     // B
     {
       FieldElement elementB = unitElement.getEnum("B").getField('B2');
       EnumConstantDeclaration nodeB = elementB.computeNode();
       expect(nodeB, isNotNull);
       expect(nodeB.name.name, "B2");
       expect(nodeB.element, same(elementB));
     }
   }
+
+  void test_isEnumConstant() {
+    AnalysisContextHelper contextHelper = new AnalysisContextHelper();
+    AnalysisContext context = contextHelper.context;
+    Source source = contextHelper.addSource(
+        "/test.dart",
+        r'''
+enum B {B1, B2, B3}
+''');
+    // prepare CompilationUnitElement
+    LibraryElement libraryElement = context.computeLibraryElement(source);
+    CompilationUnitElement unitElement = libraryElement.definingCompilationUnit;
+
+    FieldElement b2Element = unitElement.getEnum("B").getField('B2');
+    expect(b2Element.isEnumConstant, isTrue);
+
+    FieldElement indexElement = unitElement.getEnum("B").getField('index');
+    expect(indexElement.isEnumConstant, isFalse);
+  }
 }
 
 @reflectiveTest
 class FunctionTypeImplTest extends EngineTestCase {
   void test_creation() {
     expect(
         new FunctionTypeImpl(
             new FunctionElementImpl.forNode(AstTestFactory.identifier3("f"))),
         isNotNull);
   }
@@ skipping 3152 matching lines @@
 }
 
 class _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction
     extends InterfaceTypeImpl {
   _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction(ClassElement arg0)
       : super(arg0);
 
   @override
   bool get isDartCoreFunction => true;
 }