Add flag to disable capturing stack traces.

pkg/scheduled_test/test/scheduled_test/capture_stack_traces_test.dart

Index: pkg/scheduled_test/test/scheduled_test/capture_stack_traces_test.dart
diff --git a/pkg/scheduled_test/test/scheduled_test/capture_stack_traces_test.dart b/pkg/scheduled_test/test/scheduled_test/capture_stack_traces_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ea6894f87146ec38d2a9e7f4f76e90dfd0b96f15
--- /dev/null
+++ b/pkg/scheduled_test/test/scheduled_test/capture_stack_traces_test.dart
@@ -0,0 +1,52 @@
+// 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.
+
+import 'dart:async';
+import 'dart:io' hide sleep;
+
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../metatest.dart';
+import '../utils.dart';
+
+void main() {
+  setUpTimeout();
+
+  expectTestsPass('error includes a stack trace by default', () {
+    var error;
+    test('test 1', () {
+      currentSchedule.onComplete.schedule(() {
+        error = currentSchedule.errors.first.toString();

[nweiz, 2013/04/09 21:25:58]

To be consistent with other tests, don't convert this to a string until test 2.
Same for the test below.

[Bob Nystrom, 2013/04/10 21:52:00]

Done.

+      });
+
+      schedule(() => throw 'error');
+    });
+
+    test('test 2', () {
+      // There should be two stack traces: one for the thrown error, and one
+      // for the failed task (which is the captured one).
+      var numStackTraces = new RegExp('Stack trace:').allMatches(error).length;
+      expect(numStackTraces, equals(2));

[nweiz, 2013/04/09 21:25:58]

expect(error.toString(), stringContainsInOrder('Stack trace:', 'Stack trace:'))

Also, for future reference, a RegExp isn't necessary here; you could just use
[String.allMatches].

[Bob Nystrom, 2013/04/10 21:52:00]

Done.

+    });
+  }, passing: ['test 2']);
+
+  expectTestsPass('does not capture a stack trace if set to false', () {
+    captureStackTraces = false;
+    var error;
+    test('test 1', () {
+      currentSchedule.onComplete.schedule(() {
+        error = currentSchedule.errors.first.toString();
+      });
+
+      schedule(() => throw 'error');
+    });
+
+    test('test 2', () {
+      // There should only be the stack trace for the thrown exception, but no
+      // captured trace for the failed task.
+      var numStackTraces = new RegExp('Stack trace:').allMatches(error).length;
+      expect(numStackTraces, equals(1));

[nweiz, 2013/04/09 21:25:58]

expect(error.toString(), isNot(contains('Stack trace:')));

[Bob Nystrom, 2013/04/10 21:52:00]

It will have one instance of 'Stack trace' in it. See the above comment.

+    });
+  }, passing: ['test 2']);
+}