Tighten up dependencies in the task model.

pkg/analyzer/test/src/task/dart_test.dart

 // Copyright (c) 2015, 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 test.src.task.dart_test;
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 2320 matching lines @@
     {
       ClassElement classB = library.getType('B');
       expect(classB.supertype.displayName, 'A');
     }
     {
       ClassElement classC = library.getType('C');
       expect(classC.supertype.displayName, 'A');
     }
   }
 
-  test_perform_deep() {
+  test_perform_external() {
     Source sourceA = newSource('/a.dart', '''
 library a;
 import 'b.dart';
 class A extends B {}
 ''');
     newSource('/b.dart', '''
 library b;
-import 'c.dart';
-part 'b2.dart';
-class B extends B2 {}
+class B {}
 ''');
-    newSource('/b2.dart', '''
-part of b;
-class B2 extends C {}
-''');
-    newSource('/c.dart', '''
-library c;
-class C {}
-''');
+    // The reference A to B should be resolved, but there's no requirement that
+    // the full class hierarchy be resolved.
     computeResult(sourceA, LIBRARY_ELEMENT5);
     expect(task, new isInstanceOf<ResolveLibraryTypeNamesTask>());
     // validate
     LibraryElement library = outputs[LIBRARY_ELEMENT5];
     {
       ClassElement clazz = library.getType('A');
       expect(clazz.displayName, 'A');
       clazz = clazz.supertype.element;
       expect(clazz.displayName, 'B');
-      clazz = clazz.supertype.element;
-      expect(clazz.displayName, 'B2');
-      clazz = clazz.supertype.element;
-      expect(clazz.displayName, 'C');
-      clazz = clazz.supertype.element;
-      expect(clazz.displayName, 'Object');
-      expect(clazz.supertype, isNull);
     }
   }
 }
 
 @reflectiveTest
 class ResolveReferencesTaskTest extends _AbstractDartTaskTest {
   test_perform() {
     Source source = newSource('/test.dart', '''
 class A {
   m() {}
@@ skipping 409 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result];
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }