Fix analyzer hints and warnings in test/.

test/utils_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 utils_test;
 
 import 'package:pub/src/utils.dart';
 import 'package:test/test.dart';
 
-import 'test_pub.dart';
-
 main() {
   group('yamlToString()', () {
     test('null', () {
       expect(yamlToString(null), equals('null'));
     });
 
     test('numbers', () {
       expect(yamlToString(123), equals('123'));
       expect(yamlToString(12.34), equals('12.34'));
     });
@@ skipping 59 matching lines @@
     });
 
     test('handles empty maps', () {
       expect(yamlToString({}), equals("{}"));
       expect(yamlToString({'a': {}, 'b': {}}), equals("""
 a: {}
 b: {}"""));
     });
   });
 }