Make is_django_unittest more straightforward

pytest_django/django_compat.py

@@ -1,22 +1,17 @@
 # Note that all functions here assume django is available.  So ensure
 # this is the case before you call them.
-import sys
 
 
-def is_django_unittest(item):
-    """Returns True if the item is a Django test case, otherwise False"""
+def is_django_unittest(request_or_item):
+    """Returns True if the request_or_item is a Django test case, otherwise False"""
     try:
         from django.test import SimpleTestCase as TestCase
     except ImportError:
         from django.test import TestCase
 
-    if not hasattr(item, 'obj'):
-        return False
+    cls = getattr(request_or_item, 'cls', None)
 
-    if sys.version_info < (3, 0):
-        return (hasattr(item.obj, 'im_class') and
-                issubclass(item.obj.im_class, TestCase))
+    if cls is None:
+        return False
 
-    return (hasattr(item.obj, '__self__') and
-            hasattr(item.obj.__self__, '__class__') and
-            issubclass(item.obj.__self__.__class__, TestCase))
+    return issubclass(cls, TestCase)

pytest_django/fixtures.py

@@ -58,7 +58,7 @@ def teardown_database():
 
 
 def _django_db_fixture_helper(transactional, request, _django_cursor_wrapper):
-    if is_django_unittest(request.node):
+    if is_django_unittest(request):
         return
 
     if transactional:

pytest_django/plugin.py

@@ -268,7 +268,7 @@ def _django_db_marker(request):
 @pytest.fixture(autouse=True)
 def _django_setup_unittest(request, _django_cursor_wrapper):
     """Setup a django unittest, internal to pytest-django"""
-    if django_settings_is_configured() and is_django_unittest(request.node):
+    if django_settings_is_configured() and is_django_unittest(request):
         request.getfuncargvalue('_django_test_environment')
         request.getfuncargvalue('_django_db_setup')
         _django_cursor_wrapper.enable()