Use helper methods for running pub.

sdk/lib/_internal/pub/test/install/broken_symlink_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 pub_tests;
 
 import 'dart:io';
 
 import 'package:pathos/path.dart' as path;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
   integration('replaces a broken "packages" symlink', () {
     d.dir(appPath, [
       d.appPubspec([]),
       d.libDir('foo'),
       d.dir("bin")
     ]).create();
 
     // Create a broken "packages" symlink in "bin".
     scheduleSymlink("nonexistent", path.join(appPath, "packages"));
 
-    schedulePub(args: ['install'],
-        output: new RegExp(r"Dependencies installed!$"));
+    pubInstall();
 
     d.dir(appPath, [
       d.dir("bin", [
         d.dir("packages", [
           d.dir("myapp", [
             d.file('foo.dart', 'main() => "foo";')
           ])
         ])
       ])
     ]).validate();
   });
 
   integration('replaces a broken secondary "packages" symlink', () {
     d.dir(appPath, [
       d.appPubspec([]),
       d.libDir('foo'),
       d.dir("bin")
     ]).create();
 
     // Create a broken "packages" symlink in "bin".
     scheduleSymlink("nonexistent", path.join(appPath, "bin", "packages"));
 
-    schedulePub(args: ['install'],
-        output: new RegExp(r"Dependencies installed!$"));
+    pubInstall();
 
     d.dir(appPath, [
       d.dir("bin", [
         d.dir("packages", [
           d.dir("myapp", [
             d.file('foo.dart', 'main() => "foo";')
           ])
         ])
       ])
     ]).validate();
   });
 }