model._string_constraints: don't overwrite existing attributes in cas…

…e of a conflict

Currently a string constraints decorator silently overwrites existing
attributes in case of a naming conflict. This behavior is changed such
that the decorator checks for existing attributes beforehand and raises
an exception in case of a conflict.
Futhermore, tests for this behavior are added.

basyx/aas/model/_string_constraints.py

@@ -130,6 +130,8 @@ def _setter(self, value: Optional[str]) -> None:
                 constraint_check_fn(value)
             setattr(self, "_" + pub_attr_name, value)
 
+        if hasattr(decorated_class, pub_attr_name):
+            raise AttributeError(f"{decorated_class.__name__} already has an attribute named '{pub_attr_name}'")
         setattr(decorated_class, pub_attr_name, property(_getter, _setter))
         return decorated_class
 

test/model/test_string_constraints.py

@@ -83,3 +83,19 @@ def test_ignore_none_values(self) -> None:
         dc = self.DummyClass(None)  # type: ignore
         self.assertIsNone(dc.some_attr)
         dc.some_attr = None  # type: ignore
+
+    def test_attribute_name_conflict(self) -> None:
+        # We don't want to overwrite existing attributes in case of a name conflict
+        with self.assertRaises(AttributeError) as cm:
+            @_string_constraints.constrain_revision_type("foo")
+            class DummyClass:
+                foo = property()
+        self.assertEqual("DummyClass already has an attribute named 'foo'", cm.exception.args[0])
+
+        with self.assertRaises(AttributeError) as cm:
+            @_string_constraints.constrain_label_type("bar")
+            class DummyClass2:
+                @property
+                def bar(self):
+                    return "baz"
+        self.assertEqual("DummyClass2 already has an attribute named 'bar'", cm.exception.args[0])