Enable lazy senders by inheriting ModelSignal (#65)

Author: rpkilby

django_fsm/signals.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from django.dispatch import Signal
+from django.db.models.signals import ModelSignal
 
-pre_transition = Signal()
-post_transition = Signal()
+pre_transition = ModelSignal()
+post_transition = ModelSignal()

tests/testapp/tests/test_basic_transitions.py

@@ -152,6 +152,15 @@ def test_signals_not_called_on_invalid_transition(self):
         assert not self.post_transition_called
 
 
+class LazySenderTests(StateSignalsTests):
+    def setUp(self):
+        self.model = SimpleBlogPost()
+        self.pre_transition_called = False
+        self.post_transition_called = False
+        pre_transition.connect(self.on_pre_transition, sender="testapp.SimpleBlogPost")
+        post_transition.connect(self.on_post_transition, sender="testapp.SimpleBlogPost")
+
+
 class TestFieldTransitionsInspect(TestCase):
     def setUp(self):
         self.model = SimpleBlogPost()