fix: SubsidyAPIHTTPError should not drop the HTTP response error

enterprise_access/apps/api/v1/tests/test_subsidy_access_policy_views.py

@@ -13,6 +13,7 @@
 from rest_framework import status
 from rest_framework.reverse import reverse
 
+from enterprise_access.apps.api_client.tests.test_utils import MockResponse
 from enterprise_access.apps.content_assignments.constants import LearnerContentAssignmentStateChoices
 from enterprise_access.apps.content_assignments.tests.factories import (
     AssignmentConfigurationFactory,
@@ -2005,13 +2006,17 @@ def test_can_redeem_subsidy_client_http_error(self, mock_get_client):
         query_params = {'content_key': test_content_key}
 
         mock_client = mock_get_client.return_value
-        mock_client.list_subsidy_transactions.side_effect = HTTPError
+        mock_client.list_subsidy_transactions.side_effect = HTTPError(
+            'Fake HTTP Error Message',
+            response=MockResponse({'detail': 'foobar'}, status.HTTP_503_SERVICE_UNAVAILABLE),
+        )
 
         response = self.client.get(self.subsidy_access_policy_can_redeem_endpoint, query_params)
 
         assert response.status_code == status.HTTP_422_UNPROCESSABLE_ENTITY
         assert response.json() == {
-            'detail': 'Subsidy Transaction API error: HTTPError occurred in Subsidy API request.',
+            'detail': 'Subsidy Transaction API error: foobar',
+            'subsidy_status_code': str(status.HTTP_503_SERVICE_UNAVAILABLE),
         }
 
 

enterprise_access/apps/subsidy_access_policy/exceptions.py

@@ -42,12 +42,24 @@ class SubsidyAPIHTTPError(requests.exceptions.HTTPError):
     """
     @property
     def error_response(self):
-        """ Fetch the response object from the HTTPError that caused this exception. """
+        """
+        Fetch the response object from the HTTPError that caused this exception.
+
+        Returns:
+            requests.models.Response or None.
+        """
         return self.__cause__.response  # pylint: disable=no-member
 
     def error_payload(self):
-        if self.error_response:
-            return self.error_response.json()
+        """
+        Generate a useful error payload for logging purposes.
+        """
+        # requests.models.Response is falsey for HTTP status codes greater than or equal to 400!  We must explicitly
+        # check if the response object is not None before giving up on it.
+        if self.error_response is not None:
+            error_payload = self.error_response.json()
+            error_payload['subsidy_status_code'] = self.error_response.status_code
+            return error_payload
         return {
             'detail': str(self),
         }