Fix recomputing LibraryElement.exportNamespace.

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';
@@ skipping 283 matching lines @@
     }
     // Adding the source as a changedSource should have no effect since
     // it is already overridden in the content cache.
     ChangeSet changeSet = new ChangeSet();
     changeSet.changedSource(source);
     ApplyChangesStatus changesStatus = context.applyChanges(changeSet);
     expect(changesStatus.hasChanges, isFalse);
     expect(context.sourcesNeedingProcessing, hasLength(0));
   }
 
+  void test_applyChanges_recompute_exportNamespace() {
+    Source libSource = addSource(
+        "/lib.dart",
+        r'''
+class A {}
+''');
+    Source exporterSource = addSource(
+        "/exporter.dart",
+        r'''
+export 'lib.dart';
+''');
+    _performPendingAnalysisTasks();
+    // initially: A
+    {
+      LibraryElement libraryElement =
+          context.getResult(exporterSource, LIBRARY_ELEMENT1) as LibraryElement;
+      expect(libraryElement.exportNamespace.definedNames.keys,
+          unorderedEquals(['A']));
+    }
+    // after update: B
+    context.setContents(
+        libSource,
+        r'''
+class B {}''');
+    _performPendingAnalysisTasks();
+    {
+      LibraryElement libraryElement =
+          context.getResult(exporterSource, LIBRARY_ELEMENT1) as LibraryElement;
+      expect(libraryElement.exportNamespace.definedNames.keys,
+          unorderedEquals(['B']));
+    }
+  }
+
   Future test_applyChanges_remove() {
     SourcesChangedListener listener = new SourcesChangedListener();
     context.onSourcesChanged.listen(listener.onData);
     String libAContents = r'''
 library libA;
 import 'libB.dart';''';
     Source libA = addSource("/libA.dart", libAContents);
     String libBContents = "library libB;";
     Source libB = addSource("/libB.dart", libBContents);
     LibraryElement libAElement = context.computeLibraryElement(libA);
@@ skipping 2880 matching lines @@
    * Initialize the visitor.
    */
   _ElementGatherer();
 
   @override
   void visitElement(Element element) {
     elements[element] = element;
     super.visitElement(element);
   }
 }