pkg/matcher: upgrate tests to test

test/core_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.core_matchers_test;
 
 import 'package:matcher/matcher.dart';
-import 'package:unittest/unittest.dart' show test, group;
+import 'package:test/test.dart' show test, group;
 
 import 'test_utils.dart';
 
 void main() {
   test('isTrue', () {
     shouldPass(true, isTrue);
     shouldFail(false, isTrue, "Expected: true Actual: <false>");
   });
 
   test('isFalse', () {
@@ skipping 174 matching lines @@
     w.price = 10;
     shouldPass(w, new HasPrice(10));
     shouldPass(w, new HasPrice(greaterThan(0)));
     shouldFail(w, new HasPrice(greaterThan(10)),
         "Expected: Widget with a price that is a value greater than <10> "
         "Actual: <Instance of 'Widget'> "
         "Which: has price with value <10> which is not "
         "a value greater than <10>");
   });
 }