Fix analyzer hints and warnings in test/.

test/barback/fails_if_args_with_all_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.
 
 import 'package:pub/src/exit_codes.dart' as exit_codes;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
-import '../test_pub.dart';
 import 'utils.dart';
 
 main() {
   setUp(() {
     d.appDir().create();
   });
 
   pubBuildAndServeShouldFail("if a directory is passed with --all",
       args: ["example", "--all"],
       error: 'Directory names are not allowed if "--all" is passed.',
       exitCode: exit_codes.USAGE);
 }