Fix analyzer hints and warnings in test/.

test/preprocess_test.dart

 // Copyright (c) 2014, 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 pub.test.preprocess_test;
 
 import 'package:pub/src/preprocess.dart';
 import 'package:pub_semver/pub_semver.dart';
 import 'package:test/test.dart';
 
-import 'test_pub.dart';
-
 main() {
   test("does nothing on a file without preprocessor directives", () {
     var text = '''
 some text
 // normal comment
 // #
  //# not beginning of line
 ''';
 
     expect(_preprocess(text), equals(text));
@@ skipping 269 matching lines @@
 //# else barback <0.5.0
 //# end
 '''), throwsFormatException);
       });
     });
   });
 }
 
 String _preprocess(String input) =>
     preprocess(input, {'barback': new Version.parse("1.2.3")}, 'source/url');