Fix tests: Intermittent FK constraint violation on polymorphic_ctype_id

mailing/tests/test_forms.py

@@ -1,5 +1,6 @@
 """Tests for mailing app forms."""
 from django.test import TestCase
+from django.contrib.contenttypes.models import ContentType
 
 from mailing.tests.forms import TestBaseEmailTemplateForm
 
@@ -13,6 +14,10 @@ def setUp(self):
             "internal_name": "notification 01",
         }
 
+    def tearDown(self):
+        super().tearDown()
+        ContentType.objects.clear_cache()
+
     def test_validate_required_fields(self):
         required = set(self.data)
         form = TestBaseEmailTemplateForm(data={})

pydotorg/settings/local.py

@@ -63,3 +63,5 @@
 REST_FRAMEWORK['DEFAULT_RENDERER_CLASSES'] += (
     'rest_framework.renderers.BrowsableAPIRenderer',
 )
+
+BAKER_CUSTOM_CLASS = "pydotorg.tests.baker.PolymorphicAwareBaker"

pydotorg/tests/baker.py

@@ -0,0 +1,17 @@
+from polymorphic.models import PolymorphicModel
+from model_bakery import baker
+
+
+class PolymorphicAwareBaker(baker.Baker):
+    """
+    Our custom model baker ignores the polymorphic_ctype field on all polymorphic
+    models - this allows the base class to set it correctly.
+
+    See https://github.com/python/pythondotorg/issues/2567
+    """
+
+    def get_fields(self):
+        fields = super().get_fields()
+        if issubclass(self.model, PolymorphicModel):
+            fields = {field for field in fields if field.name != "polymorphic_ctype"}
+        return fields