Address review: tighten test assertions, fix RackTypeImportForm, style consistency

Per code review on the PR:

- The POST half of both new regression tests asserted only that the field
  name appeared in response.data, which the pre-fix "cannot be blank" error
  also satisfies (same key, different error code). Tightened both to assert
  the DRF error code is 'required', so the tests actually fail on main.

- RackTypeImportForm.form_factor (CSV bulk import) had the same required=False
  mismatch as the REST API fields this PR fixes, but worse: Django's
  BaseModelForm._get_validation_exclusions() skips full_clean() validation for
  a blank=False model field whose form field is required=False and empty, so
  a CSV row omitting form_factor silently saved a RackType with
  form_factor='' instead of erroring. Confirmed empirically. Removed
  required=False; added a regression test, and fixed the existing
  RackTypeTestCase.csv_data fixture in test_views.py, which was already
  omitting form_factor and passing only because nothing checked the result.
  (RackImportForm.form_factor is untouched -- Rack.form_factor is genuinely
  optional/nullable, unlike RackType's.)

- Made RackTypeSerializer.form_factor's required=True explicit, matching
  L2VPNSerializer.type's style, instead of relying on ChoiceField's implicit
  default.

netbox/dcim/api/serializers_/racks.py

@@ -88,7 +88,7 @@ class RackBaseSerializer(PrimaryModelSerializer):
 class RackTypeSerializer(RackBaseSerializer):
     # Unlike Rack.form_factor (optional & nullable), RackType.form_factor is required
     # (blank=False, no default), so override RackBaseSerializer's optional declaration.
-    form_factor = ChoiceField(choices=RackFormFactorChoices)
+    form_factor = ChoiceField(choices=RackFormFactorChoices, required=True)
     manufacturer = ManufacturerSerializer(nested=True)
     rack_count = serializers.IntegerField(read_only=True)
 

netbox/dcim/forms/bulk_import.py

@@ -225,7 +225,6 @@ class RackTypeImportForm(PrimaryModelImportForm):
     form_factor = CSVChoiceField(
         label=_('Type'),
         choices=RackFormFactorChoices,
-        required=False,
         help_text=_('Form factor')
     )
     starting_unit = forms.IntegerField(

netbox/dcim/tests/test_api.py

@@ -1226,7 +1226,7 @@ class RackTypeTestCase(APIViewTestCases.APIViewTestCase):
         }
         response = self.client.post(self._get_list_url(), data, format='json', **self.header)
         self.assertHttpStatus(response, status.HTTP_400_BAD_REQUEST)
-        self.assertIn('form_factor', response.data)
+        self.assertEqual(response.data['form_factor'][0].code, 'required')
 
 
 class RackTestCase(APIViewTestCases.APIViewTestCase):

netbox/dcim/tests/test_views.py

@@ -503,10 +503,10 @@ class RackTypeTestCase(ViewTestCases.PrimaryObjectViewTestCase):
         }
 
         cls.csv_data = (
-            "manufacturer,model,slug,width,u_height,weight,max_weight,weight_unit",
-            "Manufacturer 1,RackType 4,rack-type-4,19,42,100,2000,kg",
-            "Manufacturer 1,RackType 5,rack-type-5,19,42,100,2000,kg",
-            "Manufacturer 1,RackType 6,rack-type-6,19,42,100,2000,kg",
+            "manufacturer,model,slug,form_factor,width,u_height,weight,max_weight,weight_unit",
+            f"Manufacturer 1,RackType 4,rack-type-4,{RackFormFactorChoices.TYPE_CABINET},19,42,100,2000,kg",
+            f"Manufacturer 1,RackType 5,rack-type-5,{RackFormFactorChoices.TYPE_CABINET},19,42,100,2000,kg",
+            f"Manufacturer 1,RackType 6,rack-type-6,{RackFormFactorChoices.TYPE_CABINET},19,42,100,2000,kg",
         )
 
         cls.csv_update_data = (
@@ -531,6 +531,30 @@ class RackTypeTestCase(ViewTestCases.PrimaryObjectViewTestCase):
             'comments': 'New comments',
         }
 
+    def test_bulk_import_objects_without_form_factor(self):
+        """
+        A CSV import row omitting form_factor must be rejected, not silently saved
+        with form_factor=''.
+        """
+        obj_perm = ObjectPermission(name='Test permission', actions=['add'])
+        obj_perm.save()
+        obj_perm.users.add(self.user)
+        obj_perm.object_types.add(ObjectType.objects.get_for_model(self.model))
+
+        initial_count = self._get_queryset().count()
+        csv_data = (
+            "manufacturer,model,slug,width,u_height,weight,max_weight,weight_unit",
+            "Manufacturer 1,RackType Missing Form Factor,rack-type-missing-form-factor,19,42,100,2000,kg",
+        )
+        data = {
+            'data': '\n'.join(csv_data),
+            'format': ImportFormatChoices.CSV,
+            'csv_delimiter': CSVDelimiterChoices.AUTO,
+        }
+        response = self.client.post(self._get_url('bulk_import'), data)
+        self.assertHttpStatus(response, 200)
+        self.assertEqual(self._get_queryset().count(), initial_count)
+
 
 class RackTestCase(ViewTestCases.PrimaryObjectViewTestCase):
     model = Rack

netbox/vpn/tests/test_api.py

@@ -619,7 +619,7 @@ class L2VPNTestCase(APIViewTestCases.APIViewTestCase):
         }
         response = self.client.post(self._get_list_url(), data, format='json', **self.header)
         self.assertHttpStatus(response, status.HTTP_400_BAD_REQUEST)
-        self.assertIn('type', response.data)
+        self.assertEqual(response.data['type'][0].code, 'required')
 
 
 class L2VPNTerminationTestCase(APIViewTestCases.APIViewTestCase):