Fix issues with may_<strigger> for nested and async machines and slightly improve typing

Changelog.md

@@ -9,6 +9,9 @@
 - '_anchor' suffix has been removed for (py)graphviz cluster node anchors
 - local testing switched from [tox](https://github.com/tox-dev/tox) to [nox](https://github.com/wntrblm/nox)
 - PR #633: Remove surrounding whitespace from docstrings (thanks @artofhuman)
+- Typing:
+  + Made machine property mandatory in (Nested)EventData
+  + Transition.dest may be None
 
 ## 0.9.0 (September 2022)
 

tests/test_async.py

@@ -498,6 +498,21 @@ async def run():
 
         asyncio.run(run())
 
+    def test_may_transition_internal(self):
+        states = ['A', 'B', 'C']
+        d = DummyModel()
+        _ = self.machine_cls(model=d, states=states, transitions=[["go", "A", "B"], ["wait", "B", None]],
+                             initial='A', auto_transitions=False)
+
+        async def run():
+            assert await d.may_go()
+            assert not await d.may_wait()
+            await d.go()
+            assert not await d.may_go()
+            assert await d.may_wait()
+
+        asyncio.run(run())
+
 
 @skipIf(asyncio is None or (pgv is None and gv is None), "AsyncGraphMachine requires asyncio and (py)gaphviz")
 class TestAsyncGraphMachine(TestAsync):

tests/test_nesting.py

@@ -910,6 +910,7 @@ def test_machine_may_transitions(self):
         transitions = [
             {'trigger': 'walk', 'source': 'A', 'dest': 'B'},
             {'trigger': 'run', 'source': 'B', 'dest': 'C'},
+            {'trigger': 'wait', 'source': 'B', 'dest': None},
             {'trigger': 'run_fast', 'source': 'C', 'dest': 'C{0}1'.format(self.separator)},
             {'trigger': 'sprint', 'source': 'C', 'dest': 'D'}
         ]
@@ -920,11 +921,13 @@ def test_machine_may_transitions(self):
         assert not m.may_run()
         assert not m.may_run_fast()
         assert not m.may_sprint()
+        assert not m.may_wait()
 
         m.walk()
         assert not m.may_walk()
         assert m.may_run()
         assert not m.may_run_fast()
+        assert m.may_wait()
 
         m.run()
         assert m.may_run_fast()

transitions/core.py

@@ -884,7 +884,7 @@ def _can_trigger(self, model, trigger, *args, **kwargs):
                 continue
             for transition in self.events[trigger_name].transitions[state]:
                 try:
-                    _ = transition.source if transition.dest is None else self.get_state(transition.dest)
+                    _ = self.get_state(transition.dest) if transition.dest is not None else transition.source
                 except ValueError:
                     continue
 

transitions/core.pyi

@@ -51,7 +51,7 @@ class Transition:
     dynamic_methods: List[str]
     condition_cls: Type[Condition]
     source: str
-    dest: str
+    dest: Optional[str]
     prepare: CallbackList
     before: CallbackList
     after: CallbackList
@@ -70,7 +70,7 @@ TransitionConfig = Union[Sequence[Union[str, Any]], Dict[str, Any], Transition]
 class EventData:
     state: Optional[State]
     event: Optional[Event]
-    machine: Optional[Machine]
+    machine: Machine
     model: object
     args: Iterable[Any]
     kwargs: Dict[str, Any]

transitions/extensions/asyncio.py

@@ -433,7 +433,7 @@ async def _can_trigger(self, model, trigger, *args, **kwargs):
                 continue
             for transition in self.events[trigger_name].transitions[state]:
                 try:
-                    _ = self.get_state(transition.dest)
+                    _ = self.get_state(transition.dest) if transition.dest is not None else transition.source
                 except ValueError:
                     continue
                 await self.callbacks(self.prepare_event, evt)
@@ -559,7 +559,7 @@ async def _can_trigger_nested(self, model, trigger, path, *args, **kwargs):
                 state_name = self.state_cls.separator.join(source_path)
                 for transition in self.events[trigger].transitions.get(state_name, []):
                     try:
-                        _ = self.get_state(transition.dest)
+                        _ = self.get_state(transition.dest) if transition.dest is not None else transition.source
                     except ValueError:
                         continue
                     await self.callbacks(self.prepare_event, evt)

transitions/extensions/nesting.py

@@ -686,7 +686,7 @@ def _can_trigger_nested(self, model, trigger, path, *args, **kwargs):
                 state_name = self.state_cls.separator.join(source_path)
                 for transition in self.events[trigger].transitions.get(state_name, []):
                     try:
-                        _ = self.get_state(transition.dest)
+                        _ = self.get_state(transition.dest) if transition.dest is not None else transition.source
                     except ValueError:
                         continue
                     self.callbacks(self.prepare_event, evt)

transitions/extensions/nesting.pyi

@@ -23,7 +23,7 @@ class NestedEvent(Event):
 class NestedEventData(EventData):
     state: Optional[NestedState]
     event: Optional[NestedEvent]
-    machine: Optional[HierarchicalMachine]
+    machine: HierarchicalMachine
     transition: Optional[NestedTransition]
     source_name: Optional[str]
     source_path: Optional[List[str]]