fix(parameters): honor auto transform in batched get_parameters_by_name

aws_lambda_powertools/utilities/parameters/ssm.py

@@ -654,7 +654,12 @@ def _transform_and_cache_get_parameters_response(
 
             # NOTE: If transform is set, we do it before caching to reduce number of operations
             if transform:
-                value = transform_value(value=value, transform=transform, raise_on_transform_error=raise_on_error)  # type: ignore[assignment]
+                value = transform_value(
+                    value=value,
+                    transform=transform,
+                    raise_on_transform_error=raise_on_error,
+                    key=name,
+                )  # type: ignore[assignment]
 
             _cache_key = (name, transform)
             self.add_to_cache(key=_cache_key, value=value, max_age=options["max_age"])

tests/functional/parameters/_boto3/test_utilities_parameters.py

@@ -1142,6 +1142,34 @@ def test_ssm_provider_get_parameters_by_name_do_not_raise_on_failure_transform(m
         stubber.deactivate()
 
 
+def test_ssm_provider_get_parameters_by_name_auto_transform_infers_from_parameter_name(mock_name, mock_value, config):
+    # GIVEN transform="auto" and a parameter name suffixed with ".json"
+    # (auto-transform must infer the transform method from the parameter name, not its value)
+    success = f"/dev/{mock_name}.json"
+    fail = "/does_not_exist"  # stub model doesn't support all-success yet
+    params = {success: {}, fail: {}}
+    param_names = list(params.keys())
+    expected_value = {"value": mock_value}
+    stub_params = {success: json.dumps(expected_value)}
+
+    expected_stub_response = build_get_parameters_stub(params=stub_params, invalid_parameters=[fail])
+    expected_stub_params = {"Names": param_names}
+
+    provider = parameters.SSMProvider(boto_config=config)
+    stubber = stub.Stubber(provider.client)
+    stubber.add_response("get_parameters", expected_stub_response, expected_stub_params)
+    stubber.activate()
+
+    try:
+        ret = provider.get_parameters_by_name(parameters=params, transform="auto", raise_on_error=False)
+
+        stubber.assert_no_pending_responses()
+        # THEN the value should be parsed as JSON, not returned as a raw string
+        assert ret[success] == expected_value
+    finally:
+        stubber.deactivate()
+
+
 def test_ssm_provider_get_parameters_by_name_do_not_raise_on_failure_with_decrypt(mock_name, config):
     # GIVEN one parameter requires decryption and an arbitrary SDK error occurs
     param = f"/{mock_name}"