Add bounds check in scope lookup (issue 26633)

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 analyzer.test.generated.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 24 matching lines @@
 
 main() {
   initializeTestEnvironment();
   runReflectiveTests(AnalysisDeltaTest);
   runReflectiveTests(ChangeSetTest);
   runReflectiveTests(DisableAsyncTestCase);
   runReflectiveTests(EnclosedScopeTest);
   runReflectiveTests(ErrorResolverTest);
   runReflectiveTests(LibraryImportScopeTest);
   runReflectiveTests(LibraryScopeTest);
+  runReflectiveTests(PrefixedNamespaceTest);
   runReflectiveTests(ScopeTest);
   runReflectiveTests(StrictModeTest);
   runReflectiveTests(SubtypeManagerTest);
   runReflectiveTests(TypeOverrideManagerTest);
   runReflectiveTests(TypePropagationTest);
   runReflectiveTests(TypeProviderImplTest);
   runReflectiveTests(TypeResolverVisitorTest);
 }
 
 @reflectiveTest
@@ skipping 473 matching lines @@
   }
 
   void test_getErrorListener() {
     LibraryElement definingLibrary = createDefaultTestLibrary();
     GatheringErrorListener errorListener = new GatheringErrorListener();
     LibraryScope scope = new LibraryScope(definingLibrary, errorListener);
     expect(scope.errorListener, errorListener);
   }
 }
 
+@reflectiveTest
+class PrefixedNamespaceTest extends ResolverTestCase {
+  void test_lookup_missing() {
+    ClassElement element = ElementFactory.classElement2('A');
+    PrefixedNamespace namespace = new PrefixedNamespace('p', _toMap([element]));
+    expect(namespace.get('p.B'), isNull);
+  }
+
+  void test_lookup_missing_matchesPrefix() {
+    ClassElement element = ElementFactory.classElement2('A');
+    PrefixedNamespace namespace = new PrefixedNamespace('p', _toMap([element]));
+    expect(namespace.get('p'), isNull);
+  }
+
+  void test_lookup_valid() {
+    ClassElement element = ElementFactory.classElement2('A');
+    PrefixedNamespace namespace = new PrefixedNamespace('p', _toMap([element]));
+    expect(namespace.get('p.A'), same(element));
+  }
+
+  HashMap<String, Element> _toMap(List<Element> elements) {
+    HashMap<String, Element> map = new HashMap<String, Element>();
+    for (Element element in elements) {
+      map[element.name] = element;
+    }
+    return map;
+  }
+}
+
 class Scope_EnclosedScopeTest_test_define_duplicate extends Scope {
   GatheringErrorListener listener;
 
   Scope_EnclosedScopeTest_test_define_duplicate(this.listener) : super();
 
   @override
   AnalysisErrorListener get errorListener => listener;
 
   @override
   Element internalLookup(Identifier identifier, String name,
@@ skipping 3049 matching lines @@
  */
 class _StaleElement extends ElementImpl {
   _StaleElement() : super("_StaleElement", -1);
 
   @override
   get kind => throw "_StaleElement's kind shouldn't be accessed";
 
   @override
   accept(_) => throw "_StaleElement shouldn't be visited";
 }