Use the stack_trace library in scheduled_test.

pkg/scheduled_test/lib/src/task.dart

Index: pkg/scheduled_test/lib/src/task.dart
diff --git a/pkg/scheduled_test/lib/src/task.dart b/pkg/scheduled_test/lib/src/task.dart
index 2ce3905517a2503d4766da0133bfb7ec15fb3524..4ccb201f5fbe85af5f5f3ac19a7fe26021075cea 100644
--- a/pkg/scheduled_test/lib/src/task.dart
+++ b/pkg/scheduled_test/lib/src/task.dart
@@ -7,6 +7,8 @@ library task;
 import 'dart:async';
 import 'dart:collection';
 
+import 'package:stack_trace/stack_trace.dart';
+
 import 'future_group.dart';
 import 'schedule.dart';
 import 'utils.dart';
@@ -59,6 +61,8 @@ class Task {
   Future get result => _resultCompleter.future;
   final _resultCompleter = new Completer();
 
+  final stackTrace = new Trace.current();
+
   Task(fn(), String description, TaskQueue queue)
     : this._(fn, description, queue, null, queue.contents.length);
 
@@ -116,6 +120,11 @@ class Task {
 
   String toString() => description == null ? "#$_id" : description;
 
+  String toStringWithStackTrace() {
+    var stackString = prefixLines(terseTraceString(stackTrace));
+    return "$this\n\nStack trace:\n$stackString";
+  }
+
   /// Returns a detailed representation of [queue] with this task highlighted.
   String generateTree() => queue.generateTree(this);
 }