Added actions to execute at the end of the simulation

lib/src/simulator.dart

@@ -56,6 +56,9 @@ class Simulator {
   /// Functions to be executed as soon as possible by the [Simulator].
   static final Queue<Function()> _injectedActions = Queue<Function()>();
 
+  /// Functions to be executed at the end of the simulation.
+  static final Queue<Function()> _endOfSimulationActions = Queue<Function()>();
+
   /// Emits an event before any other actions take place on the tick.
   static Stream get preTick => _preTickController.stream;
 
@@ -133,6 +136,13 @@ class Simulator {
     _pendingTimestamps[timestamp]!.add(action);
   }
 
+  /// Registers an arbitrary [action] to be executed at the end of the simulation.
+  ///
+  /// The simulation will not be marked as ended until these actions complete.
+  static void registerEndOfSimulationAction(Function() action) {
+    _endOfSimulationActions.add(action);
+  }
+
   /// Adds an arbitrary [action] to be executed as soon as possible, during the current
   /// simulation tick if possible.
   ///
@@ -218,9 +228,16 @@ class Simulator {
         (_maxSimTime < 0 || _currentTimestamp < _maxSimTime)) {
       await tick(); // make this async so that await-ing events works
     }
+
     if (_currentTimestamp >= _maxSimTime && _maxSimTime > 0) {
       logger.warning('Simulation ended due to maximum simulation time.');
     }
+
+    while (_endOfSimulationActions.isNotEmpty) {
+      var endOfSimAction = _endOfSimulationActions.removeFirst();
+      await endOfSimAction();
+    }
+
     _simulationEndedCompleter.complete();
     await simulationEnded;
   }

test/simulator_test.dart

@@ -8,6 +8,8 @@
 /// Author: Max Korbel <max.korbel@intel.com>
 ///
 
+import 'dart:async';
+
 import 'package:rohd/rohd.dart';
 import 'package:test/test.dart';
 
@@ -56,4 +58,25 @@ void main() {
     Simulator.registerAction(100, () => true);
     await Simulator.run();
   });
+
+  test('simulator end of action waits before ending', () async {
+    var endOfSimActionExecuted = false;
+    Simulator.registerAction(100, () => true);
+    Simulator.registerEndOfSimulationAction(
+        () => endOfSimActionExecuted = true);
+    unawaited(Simulator.simulationEnded
+        .then((value) => expect(endOfSimActionExecuted, isTrue)));
+    await Simulator.run();
+  });
+
+  test('simulator end of action waits async before ending', () async {
+    var endOfSimActionExecuted = false;
+    Simulator.registerAction(100, () => true);
+    Simulator.registerEndOfSimulationAction(() async {
+      await Future.delayed(Duration(microseconds: 10));
+      endOfSimActionExecuted = true;
+    });
+    await Simulator.run();
+    expect(endOfSimActionExecuted, isTrue);
+  });
 }