Fix relation fetching when loading worlds

There was a gap in tests and the relations that came out of loading the
world were added to the lookup table in the inverse direction.
Mostly caused by a bad naming scheme and lack of tests.

Author: HexDecimal

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Unpickled worlds had reversed relations from what were saved.
 
 ## [4.2.0] - 2023-07-28
 ### Added

tcod/ecs/world.py

@@ -55,20 +55,20 @@ def _relations_lookup_from(
     relations_lookup: defaultdict[
         tuple[Any, _RelationTargetLookup] | tuple[_RelationTargetLookup, Any, None], set[Entity]
     ] = defaultdict(set)
-    for entity, tags in tags_by_entity.items():
+    for origin, tags in tags_by_entity.items():
         for tag, targets in tags.items():
             for target in targets:
-                relations_lookup[(tag, ...)].add(target)
-                relations_lookup[(tag, entity)].add(target)
-                relations_lookup[(target, tag, None)].add(entity)
-                relations_lookup[(..., tag, None)].add(entity)
-    for entity, components in components_by_entity.items():
+                relations_lookup[(tag, ...)].add(origin)
+                relations_lookup[(tag, target)].add(origin)
+                relations_lookup[(origin, tag, None)].add(target)
+                relations_lookup[(..., tag, None)].add(target)
+    for origin, components in components_by_entity.items():
         for component_key, target_components in components.items():
             for target in target_components:
-                relations_lookup[(component_key, ...)].add(target)
-                relations_lookup[(component_key, entity)].add(target)
-                relations_lookup[(target, component_key, None)].add(entity)
-                relations_lookup[(..., component_key, None)].add(entity)
+                relations_lookup[(component_key, ...)].add(origin)
+                relations_lookup[(component_key, origin)].add(origin)
+                relations_lookup[(origin, component_key, None)].add(target)
+                relations_lookup[(..., component_key, None)].add(target)
 
     return relations_lookup
 

tests/test_ecs.py

@@ -84,6 +84,10 @@ def check_world_v1(world: tcod.ecs.World) -> None:
     assert "tag" in entity.tags
     entity_b = world.named["B"]
     assert entity_b.relation_tag["ChildOf"] == entity
+    assert set(world.Q.all_of(relations=[("ChildOf", ...)])) == {entity_b}
+    assert set(world.Q.all_of(relations=[("ChildOf", entity)])) == {entity_b}
+    assert set(world.Q.all_of(relations=[(..., "ChildOf", None)])) == {entity}
+    assert set(world.Q.all_of(relations=[(entity_b, "ChildOf", None)])) == {entity}
     assert entity_b.relation_components[str][entity] == "str"
     assert not world[None].components