Use "package:" imports for pub.

test/run/errors_if_no_executable_is_given_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 '../../lib/src/exit_codes.dart' as exit_codes;
+import 'package:pub/src/exit_codes.dart' as exit_codes;
+
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration('Errors if the executable does not exist.', () {
     d.dir(appPath, [
       d.appPubspec()
     ]).create();
 
     schedulePub(args: ["run"],
         error: """
 Must specify an executable to run.
 
 Usage: pub run <executable> [args...]
 -h, --help    Print this usage information.
     --mode    Mode to run transformers in.
               (defaults to "release" for dependencies, "debug" for entrypoint)
 
 Run "pub help" to see global options.
 """,
         exitCode: exit_codes.USAGE);
   });
 }