Start pulling pub from its own repo.

sdk/lib/_internal/pub/test/transformer/prints_a_transform_interface_error_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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_tests;
-
-import '../descriptor.dart' as d;
-import '../test_pub.dart';
-import '../serve/utils.dart';
-
-final transformer = """
-import 'dart:async';
-
-import 'package:barback/barback.dart';
-
-class RewriteTransformer extends Transformer {
-  RewriteTransformer.asPlugin();
-
-  String get allowedExtensions => '.txt';
-}
-""";
-
-main() {
-  initConfig();
-  withBarbackVersions("any", () {
-    integration("prints a transform interface error", () {
-      d.dir(appPath, [
-        d.pubspec({
-          "name": "myapp",
-          "transformers": ["myapp/src/transformer"]
-        }),
-        d.dir("lib", [d.dir("src", [
-          d.file("transformer.dart", transformer)
-        ])]),
-        d.dir("web", [
-          d.file("foo.txt", "foo")
-        ])
-      ]).create();
-
-      createLockFile('myapp', pkg: ['barback']);
-
-      var server = pubServe();
-      server.stderr.expect(emitsLines(
-          "Build error:\n"
-          "Transform Rewrite on myapp|web/foo.txt threw error: Class "
-              "'RewriteTransformer' has no instance method 'apply'."));
-      endPubServe();
-    });
-  });
-}