Extract testing utilities into a separate package.

pkg/analysis_testing/lib/abstract_context.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 test.index;
+library testing.abstract_context;
 
+import 'package:analysis_testing/mock_sdk.dart';
+import 'package:analysis_testing/reflective_tests.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 
-import 'mocks.dart';
-import 'reflective_tests.dart';
-
 
 /**
  * Finds an [engine.Element] with the given [name].
  */
 Element findElementInUnit(CompilationUnit unit, String name, [ElementKind kind])
     {
   Element result = null;
   unit.element.accept(new _ElementVisitorFunctionWrapper((Element element) {
     if (element.name != name) {
       return;
@@ skipping 10 matching lines @@
 /**
  * A function to be called for every [Element].
  */
 typedef void _ElementVisitorFunction(Element element);
 
 
 @ReflectiveTestCase()
 class AbstractContextTest {
   static final DartSdk SDK = new MockSdk();
 
+  MemoryResourceProvider provider = new MemoryResourceProvider();
   AnalysisContext context;
-  MemoryResourceProvider provider = new MemoryResourceProvider();
 
   Source addSource(String path, String content) {
     File file = provider.newFile(path, content);
     Source source = file.createSource(UriKind.FILE_URI);
     ChangeSet changeSet = new ChangeSet();
     changeSet.addedSource(source);
     context.applyChanges(changeSet);
     context.setContents(source, content);
     return source;
   }
@@ skipping 20 matching lines @@
  * [engine.GeneralizingElementVisitor].
  */
 class _ElementVisitorFunctionWrapper extends GeneralizingElementVisitor {
   final _ElementVisitorFunction function;
   _ElementVisitorFunctionWrapper(this.function);
   visitElement(Element element) {
     function(element);
     super.visitElement(element);
   }
 }