Add a test runner executable.

lib/src/io.dart

 // Copyright (c) 2015, 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 unittest.io;
 
 import 'dart:async';
 import 'dart:io';
+import 'dart:isolate';

[kevmoo, 2015/02/19 01:54:08]

It seems like all of the new imports are unused.

[nweiz, 2015/02/19 02:10:18]

Done.

+
+import 'exit_codes.dart' as exit_codes;
+import 'remote_exception.dart';
 
 /// Whether "special" strings such as Unicode characters or color escapes are
 /// safe to use.
 ///
 /// On Windows or when not printing to a terminal, only printable ASCII
 /// characters should be used.
 bool get canUseSpecialChars =>
     Platform.operatingSystem != 'windows' &&
     stdioType(stdout) == StdioType.TERMINAL;
 
@@ skipping 14 matching lines @@
 /// [fn] completes to.
 Future withTempDir(Future fn(String path)) {
   return new Future.sync(() {
     // TODO(nweiz): Empirically test whether sync or async functions perform
     // better here when starting a bunch of isolates.
     var tempDir = Directory.systemTemp.createTempSync('unittest_');
     return new Future.sync(() => fn(tempDir.path))
         .whenComplete(() => tempDir.deleteSync(recursive: true));
   });
 }