Merge pull request #813 from PetrDlouhy/explicit_bakery_indication

Raise exception when usage through model_mommy/model_bakery is not explicitly indicated

docs/index.rst

@@ -25,6 +25,7 @@ Topic docs:
    utilities
    changelog
    technical_details
+   testing
 
 .. toctree::
    :maxdepth: 3

docs/testing.rst

@@ -0,0 +1,24 @@
+===================
+Testing MPTT models
+===================
+
+
+Using testing generators
+========================
+
+Using testing generators such as ``model_mommy`` or ``model_bakery`` is causing random tree fields values, which can cause unexpected behavior.
+To prevent that the ``django-mptt.MPTTModel`` will throw an Exception if made throught model_mommy/model_bakery in test environment unless
+the ``MPTT_ALLOW_TESTING_GENERATORS`` setting is set to True.
+
+You can set the ``MPTT_ALLOW_TESTING_GENERATORS`` setting to True in your Django testing settings.py file or by the ``@override_settings`` decorator for particular test.
+You would probably also have to use recipe and explicitly set the appropriate fields for the model.
+
+.. code-block:: python
+
+    from django.test import override_settings
+    from baker.recipe import Recipe
+
+    @override_settings(MPTT_ALLOW_TESTING_GENERATORS=True)
+    def test_mptt_allow_testing_generators(self):
+        my_model_recipe = Recipe(MyMPTTModel, lft=None, rght=None)
+        test_model_instance = my_model_recipe.make()

mptt/models.py

@@ -1,7 +1,10 @@
+import inspect
 import operator
+import sys
 import threading
 from functools import reduce, wraps
 
+from django.conf import settings
 from django.db import models
 from django.db.models.base import ModelBase
 from django.db.models.query import Q
@@ -437,6 +440,9 @@ class Meta:
     objects = TreeManager()
 
     def __init__(self, *args, **kwargs):
+        if hasattr(self, "_check_no_testing_generators"):
+            self._check_no_testing_generators()
+
         super().__init__(*args, **kwargs)
         self._mptt_meta.update_mptt_cached_fields(self)
 
@@ -1157,3 +1163,36 @@ def _mptt_refresh(self):
         )
         for k, v in values.items():
             setattr(self, k, v)
+
+
+def _check_no_testing_generators(self):
+    """Check that we are not generationg model from model_mommy or model_bakery"""
+    if sys.argv[1:2] == ["test"]:  # in testing envirnoment
+        curframe = inspect.currentframe()
+        call_frame = inspect.getouterframes(curframe, 0)
+        call_file = call_frame[5][1]
+        call_directory = call_file.split("/")[-2]
+        if ("model_mommy" in call_file or "model_bakery" in call_file) and not getattr(
+            settings, "MPTT_ALLOW_TESTING_GENERATORS", False
+        ):
+            raise Exception(
+                f"The {call_directory} populates django-mptt fields with random values which leads to unpredictable behavior. "
+                "If you really want to generate this model that way, please set MPTT_ALLOW_TESTING_GENERATORS=True in your settings.",
+            )
+
+
+# Use _check_no_testing_generators function only if model_mommy or model_bakery is in the path
+try:
+    import model_mommy  # noqa
+
+    MPTTModel._check_no_testing_generators = _check_no_testing_generators
+except ImportError:
+    pass
+
+
+try:
+    import model_bakery  # noqa
+
+    MPTTModel._check_no_testing_generators = _check_no_testing_generators
+except ImportError:
+    pass

tests/myapp/tests.py

@@ -11,7 +11,9 @@
 from django.db.models import Q
 from django.db.models.query_utils import DeferredAttribute
 from django.template import Context, Template, TemplateSyntaxError
-from django.test import RequestFactory, TestCase
+from django.test import RequestFactory, TestCase, override_settings
+from model_bakery import baker
+from model_mommy import mommy
 
 from mptt.admin import TreeRelatedFieldListFilter
 from mptt.querysets import TreeQuerySet
@@ -3090,3 +3092,30 @@ def test_get_user_field_names_with_not_concrete_fields(self):
         instance = NotConcreteFieldModel()
         field_names = instance._get_user_field_names()
         self.assertEqual(field_names, ["parent"])
+
+
+class BakeryTest(TestCase):
+    @override_settings(MPTT_ALLOW_TESTING_GENERATORS=True)
+    def test_create_by_bakery(self):
+        book = baker.make("Book")
+        self.assertQuerysetEqual(book.get_ancestors(), [])
+        self.assertQuerysetEqual(book.get_descendants(), [])
+        book_mommy = mommy.make("Book")
+        self.assertQuerysetEqual(book_mommy.get_ancestors(), [])
+        self.assertQuerysetEqual(book_mommy.get_descendants(), [])
+
+    def test_create_by_bakery_exception(self):
+        with self.assertRaisesRegex(
+            Exception, "^The model_bakery populates django-mptt.*"
+        ):
+            book = baker.make("Book")
+            self.assertQuerysetEqual(book.get_ancestors(), [])
+            self.assertQuerysetEqual(book.get_descendants(), [])
+
+    def test_create_by_mommy_exception(self):
+        with self.assertRaisesRegex(
+            Exception, "^The model_mommy populates django-mptt.*"
+        ):
+            book = mommy.make("Book")
+            self.assertQuerysetEqual(book.get_ancestors(), [])
+            self.assertQuerysetEqual(book.get_descendants(), [])

tests/requirements.txt

@@ -2,3 +2,5 @@ mock-django
 Django >= 2.2
 coverage
 django-js-asset
+model-bakery
+model-mommy

tox.ini

@@ -17,6 +17,8 @@ deps =
     dj32: Django>=3.2,<4.0
     dj40: Django>=4.0,<4.1
     djmain: https://github.com/django/django/archive/main.tar.gz
+    model-bakery
+    model-mommy
 
 [testenv:style]
 deps =