pkg/args: a bunch of test cleanup

pkg/args/test/command_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 command_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:args/args.dart';
+import 'utils.dart';
 
-main() {
+void main() {
   group('ArgParser.addCommand()', () {
     test('creates a new ArgParser if none is given', () {
       var parser = new ArgParser();
       var command = parser.addCommand('install');
       expect(parser.commands['install'], equals(command));
       expect(command is ArgParser, isTrue);
     });
 
     test('uses the command parser if given one', () {
       var parser = new ArgParser();
@@ skipping 176 matching lines @@
 
       var args = parser.parse(['cmd', 'subcmd', 'other', 'stuff']);
       expect(args.command.name, equals('cmd'));
       expect(args.rest, isEmpty);
       expect(args.command.command.name, equals('subcmd'));
       expect(args.command.rest, isEmpty);
       expect(args.command.command.rest, equals(['other', 'stuff']));
     });
   });
 }
-
-throwsIllegalArg(function) {
-  expect(function, throwsArgumentError);
-}
-
-throwsFormat(ArgParser parser, List<String> args) {
-  expect(() => parser.parse(args), throwsFormatException);
-}