Add test for last_used = None

Author: bouwew

tests/test_smile.py

@@ -2719,6 +2719,10 @@ async def test_adam_plus_jip(self):
 
         await self.device_test(smile, testdata)
 
+        await self.tinker_thermostat(
+            smile, "d58fec52899f4f1c92e4f8fad6d8c48c", good_schedules=[None]
+        )
+
         await smile.close_connection()
         await self.disconnect(server, client)