fix: Raise correct exception when Fn::If value is not a list (aws#2731)

samtranslator/plugins/application/serverless_app_plugin.py

@@ -1,3 +1,5 @@
+from typing import Any, Tuple
+
 import boto3
 import json
 from botocore.config import Config
@@ -73,6 +75,11 @@ def __init__(self, sar_client=None, wait_for_template_active_status=False, valid
             message = "Cannot set both validate_only and wait_for_template_active_status flags to True."
             raise InvalidPluginException(ServerlessAppPlugin.__name__, message)  # type: ignore[no-untyped-call]
 
+    @staticmethod
+    def _make_app_key(app_id: Any, semver: Any) -> Tuple[str, str]:
+        """Generate a key that is always hashable."""
+        return json.dumps(app_id, default=str), json.dumps(semver, default=str)
+
     @cw_timer(prefix=PLUGIN_METRICS_PREFIX)
     def on_before_transform_template(self, template_dict):  # type: ignore[no-untyped-def]
         """
@@ -106,15 +113,18 @@ def on_before_transform_template(self, template_dict):  # type: ignore[no-untype
                 app.properties[self.LOCATION_KEY], self.SEMANTIC_VERSION_KEY, intrinsic_resolvers
             )
 
+            key = self._make_app_key(app_id, semver)
+
             if isinstance(app_id, dict) or isinstance(semver, dict):
-                key = (json.dumps(app_id), json.dumps(semver))
                 self._applications[key] = False
                 continue
 
-            key = (app_id, semver)
-
             if key not in self._applications:
                 try:
+                    # Examine the type of ApplicationId and SemanticVersion
+                    # before calling SAR API.
+                    sam_expect(app_id, logical_id, "Location.ApplicationId").to_be_a_string()
+                    sam_expect(semver, logical_id, "Location.SemanticVersion").to_be_a_string()
                     if not RegionConfiguration.is_service_supported("serverlessrepo"):  # type: ignore[no-untyped-call]
                         raise InvalidResourceException(
                             logical_id, "Serverless Application Repository is not available in this region."
@@ -286,7 +296,7 @@ def on_before_transform_resource(self, logical_id, resource_type, resource_prope
                 "and Ref intrinsic functions are supported.",
             )
 
-        key = (app_id, semver)
+        key = self._make_app_key(app_id, semver)
 
         # Throw any resource exceptions saved from the before_transform_template event
         if isinstance(self._applications[key], InvalidResourceException):

tests/plugins/application/test_serverless_app_plugin.py

@@ -246,7 +246,7 @@ def test_sar_throttling_doesnt_stop_processing(self, SamTemplateMock):
 
         self.plugin.on_before_transform_template({})
         self.assertEqual(
-            self.plugin._applications.get(("id1", "1.0.0")).message,
+            self.plugin._applications.get(ServerlessAppPlugin._make_app_key("id1", "1.0.0")).message,
             "Resource with id [id1] is invalid. Failed to call SAR, timeout limit exceeded.",
         )
         # confirm we had at least two attempts to call SAR and that we executed a sleep

tests/translator/input/error_application_properties.yaml

@@ -43,3 +43,19 @@ Resources:
           Sub: foobar
         SemanticVersion:
           Fn::Sub: foobar
+
+  WrongTypeApplicationId:
+    Type: AWS::Serverless::Application
+    Properties:
+      Location:
+        ApplicationId:
+          - this should not be a list
+        SemanticVersion: 2.0.0
+
+  WrongTypeSemanticVersion:
+    Type: AWS::Serverless::Application
+    Properties:
+      Location:
+        ApplicationId: some-id
+        SemanticVersion:
+          - this should not be a list

tests/translator/output/error_application_properties.json

@@ -1,3 +1,3 @@
 {
-  "errorMessage": "Invalid Serverless Application Specification document. Number of errors found: 7. Resource with id [BlankProperties] is invalid. Property 'ApplicationId' is required. Resource with id [IntrinsicProperties] is invalid. Property 'ApplicationId' cannot be resolved. Only FindInMap and Ref intrinsic functions are supported. Resource with id [MissingApplicationId] is invalid. Resource is missing the required [ApplicationId] property. Resource with id [MissingLocation] is invalid. Resource is missing the required [Location] property. Resource with id [MissingSemanticVersion] is invalid. Resource is missing the required [SemanticVersion] property. Resource with id [NormalApplication] is invalid. Type of property 'ApplicationId' is invalid. Resource with id [UnsupportedProperty] is invalid. Resource is missing the required [Location] property."
+  "errorMessage": "Invalid Serverless Application Specification document. Number of errors found: 9. Resource with id [BlankProperties] is invalid. Property 'ApplicationId' is required. Resource with id [IntrinsicProperties] is invalid. Property 'ApplicationId' cannot be resolved. Only FindInMap and Ref intrinsic functions are supported. Resource with id [MissingApplicationId] is invalid. Resource is missing the required [ApplicationId] property. Resource with id [MissingLocation] is invalid. Resource is missing the required [Location] property. Resource with id [MissingSemanticVersion] is invalid. Resource is missing the required [SemanticVersion] property. Resource with id [NormalApplication] is invalid. Property 'Location.ApplicationId' should be a string. Resource with id [UnsupportedProperty] is invalid. Resource is missing the required [Location] property. Resource with id [WrongTypeApplicationId] is invalid. Property 'Location.ApplicationId' should be a string. Resource with id [WrongTypeSemanticVersion] is invalid. Property 'Location.SemanticVersion' should be a string."
 }