Display metadata about out-of-band callbacks in scheduled test errors.

pkg/scheduled_test/lib/src/schedule_error.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_error;
 
 import 'dart:async';
 
 import 'schedule.dart';
 import 'task.dart';
 import 'utils.dart';
 
 /// A wrapper for errors that occur during a scheduled test.
 class ScheduleError extends AsyncError {
   /// The schedule during which this error occurred.
   final Schedule schedule;
 
   /// The task that was running when this error occurred. This may be `null` if
   /// there was no such task.
   final Task task;
 
   /// The task queue that was running when this error occured. This may be
   /// `null` if there was no such queue.
   final TaskQueue queue;
 
+  /// The descriptions of out-of-band callbacks that were pending when this
+  /// error occurred.
+  final Collection<String> pendingCallbacks;
+
   /// The state of the schedule at the time the error was detected.
   final ScheduleState _stateWhenDetected;
 
   int get hashCode => schedule.hashCode ^ task.hashCode ^ queue.hashCode ^
       _stateWhenDetected.hashCode ^ error.hashCode ^ stackTrace.hashCode ^
       cause.hashCode;
 
   /// Creates a new [ScheduleError] wrapping [error]. The metadata in
   /// [AsyncError]s and [ScheduleError]s will be preserved.
   factory ScheduleError.from(Schedule schedule, error, {stackTrace,
       AsyncError cause}) {
     if (error is ScheduleError) return error;
 
     if (error is AsyncError) {
       // Overwrite the explicit stack trace, because it probably came from a
       // rethrow in the first place.
       stackTrace = error.stackTrace;
       if (cause == null) cause = error.cause;
       error = error.error;
     }
 
     return new ScheduleError(schedule, error, stackTrace, cause);
   }
 
   ScheduleError(Schedule schedule, error, stackTrace, AsyncError cause)
       : super.withCause(error, stackTrace, cause),
         this.schedule = schedule,

[Bob Nystrom, 2013/03/12 20:08:51]

Are the "this."s needed here?

[nweiz, 2013/03/12 20:56:51]

No, removed.

         this.task = schedule.currentTask,
         this.queue = schedule.currentQueue,
+        this.pendingCallbacks = schedule.currentQueue == null ? <String>[]
+            : new List<String>.from(schedule.currentQueue.pendingCallbacks),

[Bob Nystrom, 2013/03/12 20:08:51]

schedule.currentQueue.pendingCallbacks.toList()

[nweiz, 2013/03/12 20:56:51]

Done.

         this._stateWhenDetected = schedule.state;
 
   bool operator ==(other) => other is ScheduleError && task == other.task &&
       queue == other.queue && _stateWhenDetected == other._stateWhenDetected &&
       error == other.error && stackTrace == other.stackTrace &&
       cause == other.cause;
 
   String toString() {
     var result = new StringBuffer();
 
@@ skipping 16 matching lines @@
     } else if (_stateWhenDetected == ScheduleState.DONE) {
       result.write('Error detected after all tasks in the schedule had '
           'finished.');
     } else if (_stateWhenDetected == ScheduleState.RUNNING) {
       result.write('Error detected when waiting for out-of-band callbacks in '
           'queue "$queue".');
     } else { // _stateWhenDetected == ScheduleState.SET_UP
       result.write('Error detected before the schedule started running.');
     }
 
-    return result.toString();
+    if (!pendingCallbacks.isEmpty) {
+      result.write("\n\n");
+      result.writeln("Pending out-of-band callbacks:");
+      for (var callback in pendingCallbacks) {
+        result.writeln("* $callback");
+      }
+    }
+
+    return result.toString().trim();
   }
 }