fix: NamespaceSet.pop() removes item from all backends (#514)

pop() only removed item from first backend via popitem(), leaving stale
entries in remaining backends and causing false AASConstraintViolation
on subsequent add() for same semantic_id.

Fixes #496

Author: zrgt

sdk/basyx/aas/model/base.py

@@ -2077,8 +2077,10 @@ def discard(self, x: _NSO) -> None:
 
     def pop(self) -> _NSO:
         _, value = next(iter(self._backend.values()))[0].popitem()
+        for key_attr_name, (backend_dict, case_sensitive) in self._backend.items():
+            key_attr_value = self._get_attribute(value, key_attr_name, case_sensitive)
+            backend_dict.pop(key_attr_value, None)
         self._execute_item_del_hook(value)
-        value.parent = None
         return value
 
     def clear(self) -> None:

sdk/test/model/test_base.py

@@ -338,6 +338,18 @@ def setUp(self):
         self.namespace = self._namespace_class()
         self.namespace3 = self._namespace_class_qualifier()
 
+    def test_namespaceset_pop_removes_from_all_backends(self) -> None:
+        # set1 has two backends: id_short and semantic_id
+        self.namespace.set1.add(self.prop1)
+        popped = self.namespace.set1.pop()
+        self.assertIs(self.prop1, popped)
+        self.assertEqual(0, len(self.namespace.set1))
+        # After pop, adding a new item with the same semantic_id must NOT raise AASConstraintViolation —
+        # it would if the popped item's semantic_id entry were still in the backend
+        new_prop = model.Property("NewProp", model.datatypes.Int, semantic_id=self.propSemanticID)
+        self.namespace.set1.add(new_prop)
+        self.assertEqual(1, len(self.namespace.set1))
+
     def test_NamespaceSet(self) -> None:
         self.namespace.set1.add(self.prop1)
         self.assertEqual(1, len(self.namespace.set1))