Extract testing utilities into a separate package.

pkg/analysis_server/test/analysis_abstract.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.domain.analysis.abstract;
 
 import 'dart:async';
 
-import 'package:analyzer/file_system/file_system.dart';
-import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/domain_analysis.dart';
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_testing/mock_sdk.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/index/index.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:unittest/unittest.dart';
 
 import 'mocks.dart';
 
 
 int findIdentifierLength(String search) {
   int length = 0;
   while (length < search.length) {
@@ skipping 256 matching lines @@
   final String correction;
   AnalysisError(this.file, this.errorCode, this.offset, this.length,
       this.message, this.correction);
 
   @override
   String toString() {
     return 'NotificationError(file=$file; errorCode=$errorCode; '
         'offset=$offset; length=$length; message=$message)';
   }
 }