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..6ea9e59f9baad2ee0864a3c807437a513ee8139a
--- /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;
+      });
+
+      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).
+      expect(error.toString(),
+          stringContainsInOrder(['Stack trace:', 'Stack trace:']));
+    });
+  }, passing: ['test 2']);
+
+  expectTestsPass('does not capture a stack trace if set to false', () {
+    var error;
+    test('test 1', () {
+      currentSchedule.captureStackTraces = false;
+      currentSchedule.onComplete.schedule(() {
+        error = currentSchedule.errors.first;
+      });
+
+      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 = 'Stack trace:'.allMatches(error.toString()).length;
+      expect(numStackTraces, equals(1));
+    });
+  }, passing: ['test 2']);
+}