Add json response to entity creation error message

nailgun/entity_mixins.py

@@ -11,6 +11,7 @@
 
 from fauxfactory import gen_choice
 from inflection import pluralize
+from requests.exceptions import HTTPError, JSONDecodeError
 
 from nailgun import client, config
 from nailgun.entity_fields import IntegerField, ListField, OneToManyField, OneToOneField
@@ -947,7 +948,12 @@ def create_json(self, create_missing=None):
 
         """
         response = self.create_raw(create_missing)
-        response.raise_for_status()
+        try:
+            response.raise_for_status()
+        except HTTPError as e:
+            with contextlib.suppress(JSONDecodeError):
+                e.args += (response.json(),)
+            raise e
         return response.json()
 
     def create(self, create_missing=None):

tests/test_entity_mixins.py

@@ -3,7 +3,7 @@
 from unittest import TestCase, mock
 
 from fauxfactory import gen_integer
-from requests.exceptions import HTTPError
+from requests.exceptions import HTTPError, JSONDecodeError
 
 from nailgun import client, config, entity_mixins
 from nailgun.entity_fields import (
@@ -621,6 +621,27 @@ def test_create_json(self):
             self.assertEqual(response.raise_for_status.call_count, 1)
             self.assertEqual(response.json.call_count, 1)
 
+    def test_create_json_with_exception(self):
+        """Check what happens if the server returns an error HTTP status code for :meth:`nailgun.entity_mixins.EntityCreateMixin.create_json`."""
+        for valid_json in (True, False):
+            response = mock.Mock()
+            return_value = {"a": "b"}
+            response.raise_for_status.side_effect = HTTPError("foo")
+            if valid_json:
+                response.json.return_value = return_value
+            else:
+                response.json.side_effect = JSONDecodeError("msg", "foo", 2)
+            with mock.patch.object(
+                self.entity, 'create_raw', return_value=response
+            ), self.assertRaises(HTTPError) as error:
+                self.entity.create_json()
+            self.assertEqual(response.raise_for_status.call_count, 1)
+            self.assertEqual(response.json.call_count, 1)
+            if valid_json:
+                self.assertEqual(error.exception.args[1], return_value)
+            else:
+                self.assertEqual(len(error.exception.args), 1)
+
     def test_create(self):
         """Test :meth:`nailgun.entity_mixins.EntityCreateMixin.create`."""