Issue 21886. Make enums available outside of the defining library.

pkg/analyzer/test/generated/resolver_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 engine.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 8641 matching lines @@
 
   void test_entryPoint_none() {
     Source source = addNamedSource("/one.dart", "library one;");
     LibraryElement library = resolve(source);
     expect(library, isNotNull);
     expect(library.entryPoint, isNull);
     assertNoErrors(source);
     verify([source]);
   }
 
+  void test_enum_externalLibrary() {
+    resetWithEnum();
+    addNamedSource("/my_lib.dart", r'''
+library my_lib;
+enum EEE {A, B, C}''');
+    Source source = addSource(r'''
+import 'my_lib.dart';
+main() {
+  EEE e = null;
+}''');
+    resolve(source);
+    assertNoErrors(source);
+    verify([source]);
+  }
+
   void test_extractedMethodAsConstant() {
     Source source = addSource(r'''
 abstract class Comparable<T> {
   int compareTo(T other);
   static int compare(Comparable a, Comparable b) => a.compareTo(b);
 }
 class A {
   void sort([compare = Comparable.compare]) {}
 }''');
     resolve(source);
@@ skipping 5129 matching lines @@
         // check propagated type
         FunctionType propagatedType = node.propagatedType as FunctionType;
         expect(propagatedType.returnType, test.typeProvider.stringType);
       } on AnalysisException catch (e, stackTrace) {
         thrownException[0] = new CaughtException(e, stackTrace);
       }
     }
     return null;
   }
 }