Correctly match and print strings with escaped values

test/pretty_print_test.dart

 // Copyright (c) 2013, 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 matcher.pretty_print_test;
 
 import 'package:matcher/matcher.dart';
 import 'package:matcher/src/pretty_print.dart';
 import 'package:unittest/unittest.dart' show group, test;
 
@@ skipping 12 matching lines @@
     });
 
     test('containing newlines', () {
       expect(prettyPrint('foo\nbar\nbaz'), equals("'foo\\n'\n"
           "  'bar\\n'\n"
           "  'baz'"));
     });
 
     test('containing escapable characters', () {
       expect(
-          prettyPrint("foo\rbar\tbaz'qux"), equals("'foo\\rbar\\tbaz\\'qux'"));
+          prettyPrint("foo\rbar\tbaz'qux\v"), equals(r"'foo\rbar\tbaz\'qux\v'"));
     });
   });
 
   group('with an iterable', () {
     test('containing primitive objects', () {
       expect(prettyPrint([1, true, 'foo']), equals("[1, true, 'foo']"));
     });
 
     test('containing a multiline string', () {
       expect(prettyPrint(['foo', 'bar\nbaz\nbip', 'qux']), equals("[\n"
@@ skipping 141 matching lines @@
       expect(prettyPrint({'0': 1, '2': 3, '4': 5, '6': 7}, maxItems: 4),
           equals("{'0': 1, '2': 3, '4': 5, '6': 7}"));
     });
 
     test("that's over maxItems", () {
       expect(prettyPrint({'0': 1, '2': 3, '4': 5, '6': 7}, maxItems: 3),
           equals("{'0': 1, '2': 3, ...}"));
     });
   });
 }