Add a ScheduledProcess class to pkg/scheduled_test.

pkg/scheduled_test/test/metatest.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.
 
 /// A test library for testing test libraries? We must go deeper.
 ///
 /// Since unit testing code tends to use a lot of global state, it can be tough
 /// to test. This library manages it by running each test case in a child
 /// isolate, then reporting the results back to the parent isolate.
 library metatest;
 
 import 'dart:async';
 import 'dart:isolate';
 
 import 'package:pathos/path.dart' as path;
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
 
+// TODO(nweiz): get rid of this once issue 8863 is fixed.
+/// The path to the Dart executable. This is only set in a child isolate.
+String get dartExecutable => _executable;
+String _executable;
+
 /// Declares a test with the given [description] and [body]. [body] corresponds
 /// to the `main` method of a test file, and will be run in an isolate. By
 /// default, this expects that all tests defined in [body] pass, but if
 /// [passing] is passed, only tests listed there are expected to pass.
 void expectTestsPass(String description, void body(), {List<String> passing}) {
   _setUpTest(description, body, (results) {
     if (_hasError(results)) {
       throw 'Expected all tests to pass, but got error(s):\n'
           '${_summarizeTests(results)}';
     } else if (passing == null) {
@@ skipping 62 matching lines @@
 /// The cached [Future] for [_inChildIsolate].
 Future<bool> _inChildIsolateFuture;
 
 /// Returns whether or not we're running in a child isolate that's supposed to
 /// run a test.
 Future<bool> get _inChildIsolate {
   if (_inChildIsolateFuture != null) return _inChildIsolateFuture;
 
   var completer = new Completer();
   port.receive((message, replyTo) {
-    _testToRun = message;
+    _testToRun = message['testToRun'];
+    _executable = message['executable'];
     _replyTo = replyTo;
     port.close();
     completer.complete(true);
   });
 
   // TODO(nweiz): don't use a timeout here once issue 8416 is fixed.
   _inChildIsolateFuture = timeout(completer.future, 500, () {
     port.close();
     return false;
   });
   return _inChildIsolateFuture;
 }
 
 /// Runs the test described by [description] in its own isolate. Returns a map
 /// describing the results of that test run.
 Future<Map> _runInIsolate(String description) {
   // TODO(nweiz): Don't use path here once issue 8440 is fixed.
-  var future = spawnUri(path.join(path.current, new Options().script))
-      .call(description);
+  var future = spawnUri(path.join(path.current, new Options().script)).call({
+    'testToRun': description,
+    'executable': new Options().executable
+  });
   // TODO(nweiz): Remove this timeout once issue 8417 is fixed and we can
   // capture top-level exceptions.
   return timeout(future, 30 * 1000, () {
     throw 'Timed out waiting for test to complete.';
   });
 }
 
 /// Returns whether [results] (a test result map) describes a test run in which
 /// an error occurred.
 bool _hasError(Map results) {
@@ skipping 65 matching lines @@
         "message": testCase.message,
         "result": testCase.result,
         "stackTrace": testCase.stackTrace
       }).toList()
     });
   }
 
   void onInit() {}
   void onDone(bool success) {}
 }