Support subcommands in pub and pub help.

sdk/lib/_internal/pub/test/pub_cache_test.dart

 // Copyright (c) 2013, 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_cache_test;
 
 import 'package:path/path.dart' as path;
 
 import 'descriptor.dart' as d;
 import 'test_pub.dart';
 
 main() {
   initConfig();
 
   hostedDir(package) {
     return path.join(sandboxDir, cachePath, "hosted",
         "pub.dartlang.org", package);
   }
 
-  integration('running pub cache displays error message', () {
-    schedulePub(args: ['cache'],
-        output: '''
-          Inspect the system cache.
-
-          Usage: pub cache list
-          -h, --help    Print usage information for this command.
-          ''',
-        error: 'The cache command expects one argument.',
-        exitCode: 64);
-  });
-
-  integration('running pub cache foo displays error message', () {
-    schedulePub(args: ['cache' ,'foo'],
-        output: '''
-          Inspect the system cache.
-
-          Usage: pub cache list
-          -h, --help    Print usage information for this command.
-          ''',
-        error: 'Unknown cache command "foo".',
-        exitCode: 64);
-  });
-
   integration('running pub cache list when there is no cache', () {
     schedulePub(args: ['cache', 'list'], output: '{"packages":{}}');
   });
 
   integration('running pub cache list on empty cache', () {
     // Set up a cache.
     d.dir(cachePath, [
       d.dir('hosted', [
          d.dir('pub.dartlang.org', [
         ])
@@ skipping 40 matching lines @@
       ])
     ]).create();
 
     schedulePub(args: ['cache', 'list'], outputJson: {
       "packages": {
         "foo": {"1.2.3": {"location": hostedDir('foo-1.2.3')}}
       }
     });
   });
 }