chore: add remaining coverage

lightbulb/di/container.py

@@ -240,8 +240,6 @@ async def _get(self, dependency_id: str, *, allow_missing: bool = False) -> t.An
                 for sub_dependency_id, param_name in node_data["factory_params"].items():
                     sub_dependency = await node_data["container"]._get(sub_dependency_id, allow_missing=allow_missing)
                     if sub_dependency is _MISSING:
-                        # I'm not sure that this branch can actually be hit, but I'm going to leave it here
-                        # just in case...
                         return _MISSING
 
                     sub_dependencies[param_name] = sub_dependency

tests/di/test_container.py

@@ -414,3 +414,20 @@ async def test__contains__returns_true_when_dependency_known_by_parent(self) ->
 
         async with di.Container(r1) as r1, di.Container(r2, parent=r1) as r2:
             assert object in r2
+
+    @pytest.mark.asyncio
+    async def test_parent_dependency_returns_default_if_given_and_depends_on_child_dependency(self) -> None:
+        def f(_: A) -> object:
+            return object()
+
+        parent_registry = di.Registry()
+        parent_registry.register_factory(B, f)
+
+        child_registry = di.Registry()
+        child_registry.register_factory(A, lambda: object())
+
+        async with (
+            di.Container(parent_registry) as pc,
+            di.Container(child_registry, parent=pc) as cc,
+        ):
+            assert await cc.get(B, default=None) is None