Fix random generation of ContentType values when there is no database access

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed errors with reverse M2M relationships [PR #299](https://github.com/model-bakers/model_bakery/pull/299)
 - Fixed errors with reverse M2O relationships [PR #300](https://github.com/model-bakers/model_bakery/pull/300)
 - Improve exception message for unknown field types [PR #301](https://github.com/model-bakers/model_bakery/pull/301)
+- Fixed random generation of ContentType values when there is no database access [#290](https://github.com/model-bakers/model_bakery/pull/290)
 
 ### Removed
 

model_bakery/random_gen.py

@@ -206,7 +206,11 @@ def gen_content_type():
 
     try:
         return ContentType.objects.get_for_model(choice(apps.get_models()))
-    except AssertionError:
+    except (AssertionError, RuntimeError):
+        # AssertionError is raised by Django's test framework when db access is not available:
+        # https://github.com/django/django/blob/stable/4.0.x/django/test/testcases.py#L150
+        # RuntimeError is raised by pytest-django when db access is not available:
+        # https://github.com/pytest-dev/pytest-django/blob/v4.5.2/pytest_django/plugin.py#L709
         warnings.warn("Database access disabled, returning ContentType raw instance")
         return ContentType()
 

tests/test_baker.py

@@ -5,6 +5,7 @@
 
 import pytest
 from django.conf import settings
+from django.contrib.contenttypes.models import ContentType
 from django.db.models import Manager
 from django.db.models.signals import m2m_changed
 from django.test import TestCase, override_settings
@@ -570,7 +571,7 @@ def test_field_lookup_for_related_field_does_not_work_with_prepare(self):
         assert 0 == models.RelatedNamesModel.objects.count()
 
     def test_ensure_reverse_fk_for_many_to_one_is_working(self):
-        """This is a regression test to make sure issue 291 is fixed"""
+        """This is a regression test to make sure issue 291 is fixed."""
         fk1, fk2 = baker.prepare(
             models.Issue291Model3, fk_model_2=None, name="custom name", _quantity=2
         )
@@ -609,13 +610,23 @@ class TestHandlingContentTypeField:
     def test_create_model_with_contenttype_field(self):
         dummy = baker.make(models.DummyGenericForeignKeyModel)
         assert isinstance(dummy, models.DummyGenericForeignKeyModel)
+        assert isinstance(dummy.content_type, ContentType)
 
 
-@pytest.mark.django_db
 class TestHandlingContentTypeFieldNoQueries:
     def test_create_model_with_contenttype_field(self):
-        dummy = baker.prepare(models.DummyGenericForeignKeyModel)
+        # Clear ContentType's internal cache so that it *will* try to connect to
+        # the database in order to fetch the corresponding ContentType model for
+        # a randomly chosen model.
+        ContentType.objects.clear_cache()
+
+        with pytest.warns(
+            UserWarning,
+            match="Database access disabled, returning ContentType raw instance",
+        ):
+            dummy = baker.prepare(models.DummyGenericForeignKeyModel)
         assert isinstance(dummy, models.DummyGenericForeignKeyModel)
+        assert isinstance(dummy.content_type, ContentType)
 
 
 @pytest.mark.django_db