Add flag to disable capturing stack traces.

pkg/scheduled_test/lib/src/schedule.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.
 
 library schedule;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:stack_trace/stack_trace.dart';
 import 'package:unittest/unittest.dart' as unittest;
 
 import 'mock_clock.dart' as mock_clock;
 import 'schedule_error.dart';
+import '../scheduled_test.dart' show captureStackTraces;
 import 'substitute_future.dart';
 import 'task.dart';
 import 'utils.dart';
 import 'value_future.dart';
 
 /// The schedule of tasks to run for a single test. This has three separate task
 /// queues: [tasks], [onComplete], and [onException]. It also provides
 /// visibility into the current state of the schedule.
 class Schedule {
   /// The main task queue for the schedule. These tasks are run before the other
@@ skipping 277 matching lines @@
         currentQueue._signalTimeout(new ScheduleError.from(this, "The schedule "
             "timed out after $_timeout of inactivity."));
       });
     }
   }
 
   /// Register an error in the schedule's error list. This ensures that there
   /// are no duplicate errors, and that all errors are wrapped in
   /// [ScheduleError].
   void _addError(error) {
-    if (errors.contains(error)) return;
+    if (error is ScheduleError && errors.contains(error)) return;
     errors.add(new ScheduleError.from(this, error));
   }
 }
 
 /// An enum of states for a [Schedule].
 class ScheduleState {
   /// The schedule can have tasks added to its queue, but is not yet running
   /// them.
   static const SET_UP = const ScheduleState._("SET_UP");
 
@@ skipping 166 matching lines @@
   Function _wrapAsync(fn(arg), String description) {
     assert(_schedule.state == ScheduleState.SET_UP || isRunning);
 
     // It's possible that the queue timed out before [fn] finished.
     bool _timedOut() =>
       _schedule.currentQueue != this || pendingCallbacks.isEmpty;
 
     if (description == null) {
       description = "Out-of-band operation #${_totalCallbacks}";
     }
-    var stackString = prefixLines(terseTraceString(new Trace.current()));
-    description = "$description\n\nStack trace:\n$stackString";
+
+    if (captureStackTraces) {
+      var stackString = prefixLines(terseTraceString(new Trace.current()));
+      description += "\n\nStack trace:\n$stackString";
+    }
+
     _totalCallbacks++;
 
     _pendingCallbacks.add(description);
     return (arg) {
       try {
         return fn(arg);
       } catch (e, stackTrace) {
         var error = new ScheduleError.from(
             _schedule, e, stackTrace: stackTrace);
         if (_timedOut()) {
@@ skipping 71 matching lines @@
           return prefixLines(childString,
               firstPrefix: "  $prefix ", prefix: "  | ");
         }).join('\n');
         taskString = '$taskString\n$childrenString';
       }
 
       return taskString;
     }).join("\n");
   }
 }