pkg/matcher: upgrate tests to test

test/escape_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 matcher.escape_test;
 
 import 'package:matcher/src/util.dart';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';
 
 void main() {
   group('escaping should work with', () {
     _testEscaping('no escaped chars', 'Hello, world!', 'Hello, world!');
     _testEscaping('newline', '\n', r'\n');
     _testEscaping('carriage return', '\r', r'\r');
     _testEscaping('form feed', '\f', r'\f');
     _testEscaping('backspace', '\b', r'\b');
     _testEscaping('tab', '\t', r'\t');
     _testEscaping('vertical tab', '\v', r'\v');
@@ skipping 35 matching lines @@
     expect(s1 != s2, isTrue, reason: 'The source values should be unequal');
 
     var escapedS1 = escape(s1);
     var escapedS2 = escape(s2);
 
     // Explicitly not using the equals matcher
     expect(escapedS1 != escapedS2, isTrue,
         reason: 'Unequal strings, when escaped, should remain unequal.');
   });
 }