pkg/matcher: upgrate tests to test

test/string_matchers_test.dart

 // Copyright (c) 2012, 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.string_matchers_test;
 
 import 'package:matcher/matcher.dart';
-import 'package:unittest/unittest.dart' show test, group, expect;
+import 'package:test/test.dart' show test, group, expect;
 
 import 'test_utils.dart';
 
 void main() {
   test('Reports mismatches in whitespace and escape sequences', () {
     shouldFail('before\nafter', equals('before\\nafter'),
         contains('Differ at offset 7'));
   });
 
   test('collapseWhitespace', () {
@@ skipping 85 matching lines @@
         "Actual: 'goodbye cruel world'");
   });
 
   test('matches', () {
     shouldPass('c0d', matches('[a-z][0-9][a-z]'));
     shouldPass('c0d', matches(new RegExp('[a-z][0-9][a-z]')));
     shouldFail('cOd', matches('[a-z][0-9][a-z]'),
         "Expected: match '[a-z][0-9][a-z]' Actual: 'cOd'");
   });
 }