add ut & indentation for cross_account mpg

Author: rahven14

src/sagemaker/session.py

@@ -3222,7 +3222,9 @@ def create_model_package_from_containers(
         )
 
         def submit(request):
-            if model_package_group_name is not None and not model_package_group_name.startswith("arn:"):
+            if model_package_group_name is not None and not model_package_group_name.startswith(
+                "arn:"
+            ):
                 _create_resource(
                     lambda: self.sagemaker_client.create_model_package_group(
                         ModelPackageGroupName=request["ModelPackageGroupName"]

tests/unit/test_session.py

@@ -2650,6 +2650,18 @@ def test_create_model_package_from_containers(sagemaker_session):
     sagemaker_session.sagemaker_client.create_model_package.assert_called_once()
 
 
+def test_create_model_package_from_containers_cross_account_mpg_name(sagemaker_session):
+    mpg_name = "arn:aws:sagemaker:us-east-1:215995503607:model-package-group/stage-dev"
+    content_types = ["text/csv"]
+    response_types = ["text/csv"]
+    sagemaker_session.create_model_package_from_containers(
+        model_package_group_name=mpg_name,
+        content_types=content_types,
+        response_types=response_types,
+    )
+    sagemaker_session.sagemaker_client.create_model_package.assert_called_once()
+
+
 def test_create_model_package_from_containers_name_conflict(sagemaker_session):
     model_package_name = "sagemaker-model-package"
     model_package_group_name = "sagemaker-model-package-group"