Fix unguarded cast to an impl class (issue 26035)

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/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/handle.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptionsImpl;
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/generated/testing/ast_factory.dart';
 import 'package:analyzer/src/generated/testing/element_factory.dart';
 import 'package:analyzer/src/generated/testing/test_type_provider.dart';
 import 'package:unittest/unittest.dart';
 
@@ skipping 3675 matching lines @@
             <LibraryElement>[library, libraryA, libraryAA, libraryB]));
   }
 
   void test_getVisibleLibraries_noImports() {
     AnalysisContext context = createAnalysisContext();
     LibraryElementImpl library = ElementFactory.library(context, "app");
     expect(
         library.visibleLibraries, unorderedEquals(<LibraryElement>[library]));
   }
 
+  void test_invalidateLibraryCycles_withHandle() {
+    AnalysisContext context = createAnalysisContext();
+    context.sourceFactory = new SourceFactory([]);
+    LibraryElementImpl library = ElementFactory.library(context, "foo");
+    LibraryElementImpl importedLibrary = ElementFactory.library(context, "bar");
+    ElementLocation location = new ElementLocationImpl.con2('');
+    TestElementResynthesizer resynthesizer =
+        new TestElementResynthesizer(context, {location: importedLibrary});
+    LibraryElement importedLibraryHandle =
+        new LibraryElementHandle(resynthesizer, location);
+    ImportElementImpl import =
+        ElementFactory.importFor(importedLibraryHandle, null);
+    library.imports = <ImportElement>[import];
+    library.libraryCycle; // Force computation of the cycle.
+
+    library.invalidateLibraryCycles();
+  }
+
   void test_isUpToDate() {
     AnalysisContext context = createAnalysisContext();
     context.sourceFactory = new SourceFactory([]);
     LibraryElement library = ElementFactory.library(context, "foo");
     context.setContents(library.definingCompilationUnit.source, "sdfsdff");
     // Assert that we are not up to date if the target has an old time stamp.
     expect(library.isUpToDate(0), isFalse);
     // Assert that we are up to date with a target modification time in the
     // future.
     expect(library.isUpToDate(JavaSystem.currentTimeMillis() + 1000), isTrue);
@@ skipping 215 matching lines @@
     {
       ParameterElement element = unitElement.functions[0].parameters[0];
       SimpleFormalParameter node = element.computeNode();
       expect(node, isNotNull);
       expect(node.identifier.name, 'p');
       expect(node.element, same(element));
     }
   }
 }
 
+class TestElementResynthesizer extends ElementResynthesizer {
+  Map<ElementLocation, Element> locationMap;
+
+  TestElementResynthesizer(AnalysisContext context, this.locationMap)
+      : super(context);
+
+  @override
+  Element getElement(ElementLocation location) {
+    return locationMap[location];
+  }
+}
+
 @reflectiveTest
 class TypeParameterTypeImplTest extends EngineTestCase {
   void test_creation() {
     expect(
         new TypeParameterTypeImpl(
             new TypeParameterElementImpl.forNode(AstFactory.identifier3("E"))),
         isNotNull);
   }
 
   void test_getElement() {
@@ skipping 188 matching lines @@
 }
 
 class _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction
     extends InterfaceTypeImpl {
   _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction(ClassElement arg0)
       : super(arg0);
 
   @override
   bool get isDartCoreFunction => true;
 }