fix returning None from FindInMap (#3866)

aws-cloudformation · Dec 10, 2024 · b1ddd33 · b1ddd33
1 parent 30ecbc1
commit b1ddd33
Show file tree

Hide file tree

Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/src/cfnlint/template/transforms/_language_extensions.py b/src/cfnlint/template/transforms/_language_extensions.py
@@ -392,9 +392,12 @@ def value(
 
         if mapping:
             try:
-                return mapping.get(t_map[1].value(cfn, params, only_params), {}).get(
+                value = mapping.get(t_map[1].value(cfn, params, only_params), {}).get(
                     t_map[2].value(cfn, params, only_params)
                 )
+                if value is None:
+                    raise _ResolveError("Can't resolve Fn::FindInMap", self._obj)
+                return value
             except _ResolveError as e:
                 if len(self._map) == 4 and default_on_resolver_failure:
                     return self._map[3].value(cfn, params, only_params)

diff --git a/test/unit/module/template/transforms/test_language_extensions.py b/test/unit/module/template/transforms/test_language_extensions.py
@@ -299,6 +299,14 @@ def test_find_in_map_values_with_default(self):
         with self.assertRaises(_ResolveError):
             map.value(self.cfn, None, False, False)
 
+    def test_find_in_map_values_not_found_with_default(self):
+        map = _ForEachValueFnFindInMap(
+            "a", ["Bucket", "Production", "DNE", {"DefaultValue": "bar"}]
+        )
+
+        self.assertEqual(map.value(self.cfn, None, False, True), "bar")
+        self.assertEqual(map.value(self.cfn, None, False, False), ["foo", "bar"])
+
     def test_find_in_map_values_without_default(self):
         map = _ForEachValueFnFindInMap("a", ["Bucket", {"Ref": "Foo"}, "Key"])