raise exception if namespace does not exist in load_namespace_propert…

…ies (#477)

pyiceberg/catalog/sql.py

@@ -567,7 +567,9 @@ def load_namespace_properties(self, namespace: Union[str, Identifier]) -> Proper
         Raises:
             NoSuchNamespaceError: If a namespace with the given name does not exist.
         """
-        database_name = self.identifier_to_database(namespace, NoSuchNamespaceError)
+        database_name = self.identifier_to_database(namespace)
+        if not self._namespace_exists(database_name):
+            raise NoSuchNamespaceError(f"Database {database_name} does not exists")
 
         stmt = select(IcebergNamespaceProperties).where(
             IcebergNamespaceProperties.catalog_name == self.name, IcebergNamespaceProperties.namespace == database_name

tests/catalog/test_sql.py

@@ -726,6 +726,18 @@ def test_load_empty_namespace_properties(catalog: SqlCatalog, database_name: str
     assert listed_properties == {"exists": "true"}
 
 
+@pytest.mark.parametrize(
+    'catalog',
+    [
+        lazy_fixture('catalog_memory'),
+        lazy_fixture('catalog_sqlite'),
+    ],
+)
+def test_load_namespace_properties_non_existing_namespace(catalog: SqlCatalog) -> None:
+    with pytest.raises(NoSuchNamespaceError):
+        catalog.load_namespace_properties("does_not_exist")
+
+
 @pytest.mark.parametrize(
     'catalog',
     [