diff --git a/testing/backend/unit/test_scanners_base.py b/testing/backend/unit/test_scanners_base.py
index 38efa8397..4fbf4b602 100644
--- a/testing/backend/unit/test_scanners_base.py
+++ b/testing/backend/unit/test_scanners_base.py
@@ -153,4 +153,9 @@ def test_case_insensitive(self):
 
     def test_non_string_input(self):
         scanner = _ConcreteScanner("task21", None)
-        assert scanner.normalize_severity(123) == "info"
\ No newline at end of file
+        assert scanner.normalize_severity(123) == "info"
+
+    def test_none_input_returns_info(self):
+        """None is a common input in real pipelines — str(None)='None' is not in the mapping, so returns 'info'."""
+        scanner = _ConcreteScanner("task_none", None)
+        assert scanner.normalize_severity(None) == "info"