Add a LiveSuite class.

test/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.
 
 // TODO(nweiz): Remove this tag when we can get [packageDir] working without it
 // (dart-lang/sdk#24022).
 library test.test.io;
 
 import 'dart:async';
+import 'dart:convert';
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/descriptor.dart' as d;
 import 'package:scheduled_test/scheduled_process.dart';
 import 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:test/src/util/io.dart';
+import 'package:yaml/yaml.dart';
 
 /// The path to the root directory of the `test` package.
 final String packageDir = p.dirname(p.dirname(libraryPath(#test.test.io)));
 
 /// The path to the `pub` executable in the current Dart SDK.
 final _pubPath = p.absolute(p.join(
     p.dirname(Platform.resolvedExecutable),
     Platform.isWindows ? 'pub.bat' : 'pub'));
 
 /// The platform-specific message emitted when a nonexistent file is loaded.
@@ skipping 147 matching lines @@
     var match;
     while (match == null) {
       var line = await pub.stdout.next();
       match = _servingRegExp.firstMatch(line);
     }
     _pubServePortCompleter.complete(int.parse(match[1]));
   }, "waiting for pub serve to emit its port number");
 
   return pub;
 }