firmware: Avoid updating state.lock.since when holdopen_button=True

This should avoid MQTT messages being spammed continiously in this case
Fixes #14

firmware/dlockoslo.py

@@ -138,7 +138,7 @@ def ensure_unlocked_for_opener():
             lock = TemporarilyUnlocked(since=i.current_time, until=i.current_time+temp_unlock_time)
 
     # unlock switch
-    if i.holdopen_button == True:
+    if i.holdopen_button == True and lock.state != 'Unlocked':
         lock = Unlocked(since=i.current_time, reason='switch')
     elif i.holdopen_button == False and lock.state == 'Unlocked' and lock.reason == 'switch':
         lock = Locked(since=i.current_time, reason='switch') 

firmware/test_doorsystem.py

@@ -167,6 +167,27 @@ def test_dooropener_after_unlock():
     assert states.opener.state == 'TemporarilyActive'
 
 
+def test_holdopen_since_updates():
+    states = dlockoslo.States()
+    assert states.lock.state == 'Locked'
+    assert states.opener.state == 'Inactive'
+    inputs = dict(
+        holdopen_button=True,
+        current_time=100,
+    )
+    states = dlockoslo.next_state(states, dlockoslo.Inputs(**inputs))
+    assert states.lock.state == 'Unlocked', 'unlocks'
+    assert states.lock.since == 100, 'update since on initial transition'
+
+    inputs = dict(
+        holdopen_button=True,
+        current_time=222,
+    )
+    states = dlockoslo.next_state(states, dlockoslo.Inputs(**inputs))
+    assert states.lock.state == 'Unlocked', 'still unlocked'
+    assert states.lock.since == 100, 'dont update since when no state transition'
+
+
 def test_bolt_present_reflects_input():
     states = dlockoslo.States()
     assert states.lock.state == 'Locked'