Visualizer3D: a resource moved back to where the scene placed it publishes that location

pylabrobot/visualizer3D/server.py

@@ -368,9 +368,13 @@ def _live_loop(self) -> Optional[asyncio.AbstractEventLoop]:
   # -- state channel -----------------------------------------------------------
 
   def _placed_as_kept(self, name: str, location: Dict[str, Any]) -> bool:
-    """Whether `location` is where the kept scene already places `name`: published, but no move."""
+    """Whether `location` is where the kept scene already places `name`: published, but no move.
+
+    A resource moved since the scene was built is placed elsewhere by the clients, so its return
+    to the kept place is a move too.
+    """
     index = self._index_of.get(name)
-    if self._scene is None or index is None:
+    if self._scene is None or index is None or name in self._moved:
       return False
     return _xyz(location) == self._scene.transforms[6 * index : 6 * index + 3]
 

pylabrobot/visualizer3D/server_tests.py

@@ -264,6 +264,21 @@ async def test_a_moved_resource_publishes_its_new_position(self):
     finally:
       await ws.close()
 
+  async def test_a_resource_moved_back_to_where_the_scene_placed_it_publishes_that(self):
+    """A return to the scene's place is news to a client that was told of the move away."""
+    ws, _, _ = await self.connect()
+    try:
+      kept = self.plate.location
+      assert kept is not None
+      self.plate.location = Coordinate(400, 300, 0)
+      self.assertEqual((await self.next_state(ws))["locations"]["plate"]["x"], 400)
+      self.plate.location = kept
+      update = await self.next_state(ws)
+      self.assertIsNotNone(update)
+      self.assertEqual(update["locations"]["plate"]["x"], kept.x)
+    finally:
+      await ws.close()
+
   async def test_a_resource_moved_under_another_parent_is_moved_not_rebuilt(self):
     """The same names are the same instances: a change of parent is a move, a parent index and six
     floats, applied to the scene the client has. Its new location travels in the move and in no