cfn: add more validations to intrinsic functions

pinzon · pinzon · commit 8f1c4ef96ca5 · 2025-10-07T13:04:18.000-05:00
diff --git a/tests/aws/services/cloudformation/engine/test_conditions.py b/tests/aws/services/cloudformation/engine/test_conditions.py
@@ -1,6 +1,8 @@
+import json
 import os.path
 
 import pytest
+from botocore.exceptions import ClientError
 from tests.aws.services.cloudformation.conftest import skip_if_legacy_engine
 
 from localstack.services.cloudformation.v2.utils import is_v2_engine
@@ -515,3 +517,28 @@ def test_update_conditions(self, deploy_cfn_template, aws_client):
         assert aws_client.s3.head_bucket(Bucket=bucket_1)
         with pytest.raises(aws_client.s3.exceptions.ClientError):
             aws_client.s3.head_bucket(Bucket=bucket_2)
+
+
+class TestValidateConditions:
+    @markers.aws.validated
+    def test_validate_equals_args_len(self, aws_client, snapshot):
+        template = {
+            "Conditions": {"ShouldDeploy": {"Fn::Equals": ["a"]}},
+            "Resources": {
+                "Topic1": {
+                    "Type": "AWS::SNS::Topic",
+                },
+            },
+        }
+
+        stack_name = f"stack-{short_uid()}"
+        change_set_name = f"ch-{short_uid()}"
+        with pytest.raises(ClientError) as ex:
+            aws_client.cloudformation.create_change_set(
+                StackName=stack_name,
+                ChangeSetName=change_set_name,
+                ChangeSetType="CREATE",
+                TemplateBody=json.dumps(template),
+            )
+
+        snapshot.match("error", ex.value.response)
diff --git a/tests/aws/services/cloudformation/engine/test_conditions.validation.json b/tests/aws/services/cloudformation/engine/test_conditions.validation.json
@@ -34,5 +34,14 @@
   },
   "tests/aws/services/cloudformation/engine/test_conditions.py::TestCloudFormationConditions::test_update_conditions": {
     "last_validated_date": "2024-06-18T19:43:43+00:00"
+  },
+  "tests/aws/services/cloudformation/engine/test_conditions.py::TestValidateConditions::test_validate_equals_args_len": {
+    "last_validated_date": "2025-10-02T20:27:04+00:00",
+    "durations_in_seconds": {
+      "setup": 0.24,
+      "call": 0.32,
+      "teardown": 0.0,
+      "total": 0.56
+    }
   }
 }
