A new epheleral_condition sensor type + fix issue with dangling callback

unit_tests/test_retain_condition.py

@@ -27,6 +27,7 @@ class RetainConditionTests(unittest.TestCase):
     def setUp(self):
         self.sensor = RetainCondition()
         self.sensor.cb_handle = None
+        self.sensor._timer_generation = 0
         self.sensor.retain_time = 15
         self.sensor.reset_retain_time_on_new_success = True
         self.state = 'off'
@@ -41,6 +42,54 @@ class RetainConditionTests(unittest.TestCase):
     def set_state(self, *, state):
         self.state = state
 
+    def queued_expiry(self):
+        call = self.sensor.ad_api.run_in.call_args
+        callback = call.args[0]
+        kwargs = dict(call.kwargs)
+        return lambda: callback(kwargs)
+
+    def test_return_at_expiry_ignores_queued_callback(self):
+        self.sensor.on_condition_succeed()
+        self.sensor.on_condition_fail()
+        queued = self.queued_expiry()
+        # The scheduler has already removed the timer and queued its callback.
+        self.sensor.ad_api.cancel_timer.return_value = False
+        self.sensor.condition.evaluate.return_value = Result.Succeeded
+        self.sensor.on_condition_succeed()
+        queued()
+        self.assertEqual(self.state, 'on')
+        self.sensor.condition.evaluate.assert_not_called()
+        self.sensor.ad_api.cancel_timer.assert_called_once_with('timer', silent=True)
+
+    def test_stale_expiry_cannot_shorten_new_retention(self):
+        self.sensor.ad_api.run_in.side_effect = ['old-timer', 'new-timer']
+        self.sensor.on_condition_succeed()
+        self.sensor.on_condition_fail()
+        queued = self.queued_expiry()
+        self.sensor.on_condition_succeed()
+        self.sensor.on_condition_fail()
+        current_expiry = self.queued_expiry()
+        queued()
+        self.assertEqual(self.state, 'on')
+        self.assertEqual(self.sensor.cb_handle, 'new-timer')
+        current_expiry()
+        self.assertEqual(self.state, 'off')
+        self.assertIsNone(self.sensor.cb_handle)
+
+    def test_stale_expiry_cannot_forget_timer_while_condition_disabled(self):
+        self.sensor.ad_api.run_in.side_effect = ['old-timer', 'new-timer']
+        self.sensor.on_condition_succeed()
+        self.sensor.on_condition_fail()
+        queued = self.queued_expiry()
+        self.sensor.on_condition_succeed()
+        self.sensor.on_condition_fail()
+        self.sensor.condition.evaluate.return_value = Result.Disabled
+        queued()
+        self.assertEqual(self.sensor.cb_handle, 'new-timer')
+        self.assertEqual(self.state, 'on')
+        self.sensor.on_condition_succeed()
+        self.assertEqual(self.sensor.ad_api.cancel_timer.call_args.args, ('new-timer',))
+
     def test_long_lived_signal_gets_full_delay_after_loss(self):
         self.sensor.on_condition_succeed()
         self.assertEqual(self.state, 'on')
@@ -48,15 +97,16 @@ class RetainConditionTests(unittest.TestCase):
         # No timer can expire while the signal stays valid.
         self.sensor.on_condition_fail()
         self.assertEqual(self.state, 'on')
-        self.sensor.ad_api.run_in.assert_called_once_with(self.sensor.on_time_elapse, 15)
-        self.sensor.on_time_elapse({})
+        self.sensor.ad_api.run_in.assert_called_once_with(
+            self.sensor.on_time_elapse, 15, generation=self.sensor._timer_generation)
+        self.queued_expiry()()
         self.assertEqual(self.state, 'off')
 
     def test_returning_signal_cancels_off_and_next_loss_gets_new_delay(self):
         self.sensor.on_condition_succeed()
         self.sensor.on_condition_fail()
         self.sensor.on_condition_succeed()
-        self.sensor.ad_api.cancel_timer.assert_called_once_with('timer')
+        self.sensor.ad_api.cancel_timer.assert_called_once_with('timer', silent=True)
         self.assertIsNone(self.sensor.cb_handle)
         self.assertEqual(self.state, 'on')
         self.sensor.on_condition_fail()
@@ -79,8 +129,11 @@ class RetainConditionTests(unittest.TestCase):
             with self.subTest(result=result):
                 self.state = 'on'
                 self.sensor.condition.evaluate.return_value = result
-                self.sensor.on_time_elapse({})
+                self.sensor.register_callback()
+                self.queued_expiry()()
                 self.assertEqual(self.state, 'on')
+                self.assertIsNone(self.sensor.cb_handle)
+                self.sensor.condition.evaluate.assert_called_with()
 
     def test_explicit_no_reset_preserves_fixed_window(self):
         self.sensor.reset_retain_time_on_new_success = False
@@ -88,7 +141,7 @@ class RetainConditionTests(unittest.TestCase):
         self.sensor.on_condition_fail()
         self.assertEqual(self.state, 'on')
         self.sensor.condition.evaluate.return_value = Result.Succeeded
-        self.sensor.on_time_elapse({})
+        self.queued_expiry()()
         self.sensor.on_condition_fail()
         self.assertEqual(self.state, 'off')