Support serving from multiple directories using "pub serve".

sdk/lib/_internal/pub/test/pub_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 'package:scheduled_test/scheduled_test.dart';
 
 import '../lib/src/exit_codes.dart' as exit_codes;
 import 'test_pub.dart';
@@ skipping 191 matching lines @@
 
             Usage: pub publish [options]
             -h, --help       Print usage information for this command.
             -n, --dry-run    Validate but do not publish the package.
             -f, --force      Publish without confirmation if there are no errors.
                 --server     The package server to which to upload this package.
                              (defaults to "https://pub.dartlang.org")
             ''');
     });
 
+    integration('shows non-truncated help', () {
+      schedulePub(args: ['help', 'serve'],
+          output: '''
+            Run a local web development server.
+
+            By default, this serves "web/" and "test/", but an explicit list of 
+            directories to serve can be provided as well.
+
+            Usage: pub serve [directories...]
+            -h, --help               Print usage information for this command.
+                --port               The base port to listen on.
+                                     (defaults to "8080")
+
+                --[no-]dart2js       Compile Dart to JavaScript.
+                                     (defaults to on)
+
+                --[no-]force-poll    Force the use of a polling filesystem watcher.
+                --mode               Mode to run transformers in.
+                                     (defaults to "debug")
+            ''');
+    });
+
     integration('shows help for a subcommand', () {
       schedulePub(args: ['help', 'cache', 'list'],
           output: '''
             List packages in the system cache.
 
             Usage: pub cache list
             -h, --help    Print usage information for this command.
             ''');
     });
 
@@ skipping 41 matching lines @@
             exitCode: exit_codes.USAGE);
     });
   });
 
   group('version', () {
     integration('displays the current version', () {
       schedulePub(args: ['version'], output: VERSION_STRING);
     });
   });
 }