If conditions have no region equals just return T/F (#2721)

Author: kddejong

src/cfnlint/conditions/conditions.py

@@ -266,14 +266,24 @@ def build_scenerios_on_region(
         if not isinstance(condition_name, str):
             return
         cnf_region = self._cnf.copy()
+        found_region = False
         for eql in self._conditions[condition_name].equals:
             is_region, equal_region = eql.is_region
             if is_region:
+                found_region = True
                 if equal_region == region:
                     cnf_region.add_prop(And(self._solver_params[eql.hash]))
                 else:
                     cnf_region.add_prop(Not(self._solver_params[eql.hash]))
 
+        # The condition doesn't use a region parameter so it can be True or False
+        # Note: It is possible its a hard coded condition but
+        # for now we will return True and False
+        if not found_region:
+            yield True
+            yield False
+            return
+
         cnf_test = cnf_region.copy()
         cnf_test.add_prop(
             self._conditions[condition_name].build_true_cnf(self._solver_params)

test/unit/module/conditions/test_conditions.py

@@ -180,3 +180,52 @@ def test_check_can_be_good_when_condition_value(self):
                 {"IsGamma": False},
             ],
         )
+
+    def test_check_condition_region(self):
+        """Regional based condition testing"""
+        template = decode_str(
+            """
+        Parameters:
+          Environment:
+            Type: String
+            AllowedValues: ["prod", "dev", "stage"]
+        Conditions:
+          IsUsEast1: !Equals [!Ref AWS::Region, "us-east-1"]
+          IsUsWest2: !Equals ["us-west-2", !Ref AWS::Region]
+          IsProd: !Equals [!Ref Environment, "prod"]
+        """
+        )[0]
+
+        cfn = Template("", template)
+        self.assertEqual(len(cfn.conditions._conditions), 3)
+        self.assertListEqual(
+            list(cfn.conditions.build_scenerios_on_region("IsUsEast1", "us-east-1")),
+            [
+                True,
+            ],
+        )
+        self.assertListEqual(
+            list(cfn.conditions.build_scenerios_on_region("IsUsEast1", "us-west-2")),
+            [
+                False,
+            ],
+        )
+        self.assertListEqual(
+            list(cfn.conditions.build_scenerios_on_region("IsUsWest2", "us-west-2")),
+            [
+                True,
+            ],
+        )
+        self.assertListEqual(
+            list(cfn.conditions.build_scenerios_on_region("IsUsWest2", "us-east-1")),
+            [
+                False,
+            ],
+        )
+        self.assertListEqual(
+            list(cfn.conditions.build_scenerios_on_region("IsProd", "us-east-1")),
+            [
+                True,
+                False,
+            ],
+        )