Add check for valid comparator before looking at None

nacc_form_validator/utils.py

@@ -75,6 +75,9 @@ def compare_values(comparator: str, value: object, base_value: object) -> bool:
     if comparator == "!=":
         return value != base_value
 
+    if comparator not in ["<=", ">=", "<", ">"]:
+        raise TypeError(f"Unrecognized comparator: {comparator}")
+
     # for < and >, follow same convention as jsonlogic for null values
     # for >= and <=, allow equality case (both None)
     if value is None and base_value is None:

tests/test_utils.py

@@ -115,6 +115,10 @@ def test_compare_values_type_error():
         compare_values("*", 5, 10)
     assert str(e.value) == "Unrecognized comparator: *"
 
+    with pytest.raises(TypeError) as e:
+        compare_values("+", None, None)
+    assert str(e.value) == "Unrecognized comparator: +"
+
     with pytest.raises(TypeError) as e:
         compare_values("<", 5, parser.parse("01/01/2000"))
     assert str(e.value) == "'<' not supported between instances of 'int' and 'datetime.datetime'"