Fix the BARRIER_EMPTY singleton being mutated

src/precomp/barriers.py

@@ -364,14 +364,27 @@ def parse(cls, kv: Keyvalues, barrier_id: utils.ObjectID) -> BarrierType:
         )
 
 
+def _check_barrier_type_assignment(
+    self: Barrier,
+    attr: attrs.Attribute[BarrierType],
+    new_type: BarrierType,
+) -> None:
+    """Prevent altering BARRIER_EMPTY."""
+    try:
+        if self is BARRIER_EMPTY:
+            raise ValueError('BARRIER_EMPTY is immutable!')
+    except NameError:
+        pass   # We're constructing BARRIER_EMPTY.
+
+
 @attrs.define(eq=False, kw_only=True)
 class Barrier:
     """A glass/grating item.
 
     BARRIER_EMPTY is unique, but others may not be if created dynamically!
     """
     name: str
-    type: BarrierType
+    type: BarrierType = attrs.field(validator=_check_barrier_type_assignment)
     item: connections.Item | None = None
     instances: List[Entity] = attrs.Factory(list)
     # Set only for vanilla glass/grating items. Stores a list of the
@@ -829,6 +842,7 @@ def parse_map(vmf: VMF, conn_items: Mapping[str, connections.Item]) -> None:
     The frames are updated with a fixup var, as appropriate.
     Requires connection items to be parsed!
     """
+    LOGGER.info('Parsing barrier items...')
     frame_inst = instanceLocs.resolve_filter('[glass_frames]', silent=True)
     segment_inst = instanceLocs.resolve_filter('[glass_128]', silent=True)
     barrier_pos_lists: Dict[str, List[Tuple[PlaneKey, int, int]]] = {}
@@ -905,9 +919,8 @@ def parse_map(vmf: VMF, conn_items: Mapping[str, connections.Item]) -> None:
                     plane_pos = center + offset * norm
                     plane = PlaneKey(-norm, plane_pos)
                     local = plane.world_to_plane(plane_pos)
-                    try:
-                        barrier = BARRIERS[plane][local.x // 32, local.y // 32]
-                    except KeyError:
+                    barrier = BARRIERS[plane][local.x // 32, local.y // 32]
+                    if barrier is BARRIER_EMPTY:
                         continue  # Try other side?
                     found = True
 

src/test/test_plane.py

@@ -56,7 +56,14 @@ def _points(*pattern: str) -> List[Tuple[int, int]]:
     (3, 3), (1, 0), (0, 1), (1, 2), (2, 2), (4, 4), (0, 0), (-2, 10), (10, -5), (50, 50),
 ])
 @pytest.mark.parametrize('pattern', [
-    [(x, y) for x in  range(5) for y in range(5)],
+    [(x, y) for x in range(5) for y in range(5)],
+    _points(
+        '0...3',
+        '.....',
+        '...1.',
+        '.....',
+        '2...4',
+    ),
     _points(
         '.7..8',
         '..6..',
@@ -76,7 +83,7 @@ def _points(*pattern: str) -> List[Tuple[int, int]]:
         '..3..',
         '54..0',
     ),
-], ids=['order', 'patA', 'patB', 'patC'])
+], ids=['order', 'patA', 'patB', 'patC', 'patD'])
 def test_grid_insertion_complex(pattern: List[Tuple[int, int]], off_x: int, off_y: int) -> None:
     """Insert in various patterns, to test the dynamic resizing."""
     grid = PlaneGrid[object]()
@@ -103,6 +110,8 @@ def test_grid_insertion_complex(pattern: List[Tuple[int, int]], off_x: int, off_
         assert grid.maxes == (max_x, max_y)
         assert grid.dimensions == (max_x - min_x, max_y - min_y)
 
+        assert set(grid) == set(backup.keys())
+        assert set(grid.keys()) == set(backup.keys())
         assert dict(grid.items()) == backup
         for (chk_x, chk_y), check in backup.items():
             assert grid[chk_x, chk_y] == check, backup