Copied most of the PR pytest-dev#353 with a few adjustments, like getfixturevalue

Author: lecchri1

docs/changelog.rst

@@ -1,6 +1,15 @@
 Changelog
 =========
 
+3.2.0
+-----
+
+Features
+^^^^^^^^
+* Add support for serialized rollback in transactional tests.
+  Thanks to Piotr Karkut for `the bug report
+  <https://github.com/pytest-dev/pytest-django/issues/329>`_.
+
 3.1.2
 -----
 

docs/helpers.rst

@@ -13,8 +13,8 @@ on what marks are and for notes on using_ them.
 .. _using: https://pytest.org/en/latest/example/markers.html#marking-whole-classes-or-modules
 
 
-``pytest.mark.django_db(transaction=False)`` - request database access
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+``pytest.mark.django_db(transaction=False, serialized_rollback=False)`` - request database access
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. :py:function:: pytest.mark.django_db:
 
@@ -38,6 +38,14 @@ when trying to access the database.
  uses. When ``transaction=True``, the behavior will be the same as
  `django.test.TransactionTestCase`_
 
+:type serialized_rollback: bool
+:param serialized_rollback:
+ The ``serialized_rollback`` argument enables `rollback emulation`_.
+ After a `django.test.TransactionTestCase`_ runs, the database is
+ flushed, destroying data created in data migrations. This is the
+ default behavior of Django. Setting ``serialized_rollback=True``
+ tells Django to restore that data.
+
 .. note::
 
   If you want access to the Django database *inside a fixture*
@@ -54,6 +62,7 @@ when trying to access the database.
  Test classes that subclass Python's ``unittest.TestCase`` need to have the
  marker applied in order to access the database.
 
+.. _rollback emulation: https://docs.djangoproject.com/en/stable/topics/testing/overview/#rollback-emulation
 .. _django.test.TestCase: https://docs.djangoproject.com/en/dev/topics/testing/overview/#testcase
 .. _django.test.TransactionTestCase: https://docs.djangoproject.com/en/dev/topics/testing/overview/#transactiontestcase
 
@@ -194,6 +203,16 @@ transaction support.  This is only required for fixtures which need
 database access themselves.  A test function would normally use the
 :py:func:`~pytest.mark.django_db` mark to signal it needs the database.
 
+``serialized_rollback``
+~~~~~~~~~~~~~~~~~~~~~~~
+
+When the ``transactional_db`` fixture is enabled, this fixture can be
+added to trigger `rollback emulation`_ and thus restores data created
+in data migrations after each transaction test.  This is only required
+for fixtures which need to enforce this behavior.  A test function
+would use :py:func:`~pytest.mark.django_db(serialized_rollback=True)`
+to request this behavior.
+
 ``live_server``
 ~~~~~~~~~~~~~~~
 
@@ -203,6 +222,12 @@ or by requesting it's string value: ``unicode(live_server)``.  You can
 also directly concatenate a string to form a URL: ``live_server +
 '/foo``.
 
+Since the live server and the tests run in different threads, they
+cannot share a database transaction. For this reason, ``live_server``
+depends on the ``transactional_db`` fixture. If tests depend on data
+created in data migrations, you should add the ``serialized_rollback``
+fixture.
+
 ``settings``
 ~~~~~~~~~~~~
 

pytest_django/fixtures.py

@@ -103,7 +103,8 @@ def teardown_database():
         request.addfinalizer(teardown_database)
 
 
-def _django_db_fixture_helper(transactional, request, django_db_blocker):
+def _django_db_fixture_helper(transactional, serialized_rollback,
+                              request, django_db_blocker):
     if is_django_unittest(request):
         return
 
@@ -120,6 +121,7 @@ def _django_db_fixture_helper(transactional, request, django_db_blocker):
         from django.test import TestCase as django_case
 
     test_case = django_case(methodName='__init__')
+    test_case.serialized_rollback = serialized_rollback
     test_case._pre_setup()
     request.addfinalizer(test_case._post_teardown)
 
@@ -152,7 +154,9 @@ def db(request, django_db_setup, django_db_blocker):
             or 'live_server' in request.funcargnames:
         getfixturevalue(request, 'transactional_db')
     else:
-        _django_db_fixture_helper(False, request, django_db_blocker)
+        _django_db_fixture_helper(
+            transactional=False, serialized_rollback=False,
+            request=request, django_db_blocker=django_db_blocker)
 
 
 @pytest.fixture(scope='function')
@@ -167,7 +171,23 @@ def transactional_db(request, django_db_setup, django_db_blocker):
     database setup will behave as only ``transactional_db`` was
     requested.
     """
-    _django_db_fixture_helper(True, request, django_db_blocker)
+    serialized_rollback = False
+    if 'serialized_rollback' in request.funcargnames:
+        serialized_rollback = getfixturevalue(request, 'serialized_rollback')
+
+    _django_db_fixture_helper(
+        transactional=True, serialized_rollback=serialized_rollback,
+        request=request, django_db_blocker=django_db_blocker)
+
+
+@pytest.fixture(scope='function')
+def serialized_rollback(request):
+    """Enable serialized rollback after transaction test cases
+
+    This fixture only has an effect when the ``transactional_db``
+    fixture is active, which happen as a side-effect of requesting
+    ``live_server``.
+    """
 
 
 @pytest.fixture()

pytest_django/plugin.py

@@ -374,6 +374,8 @@ def _django_db_marker(request):
             getfixturevalue(request, 'transactional_db')
         else:
             getfixturevalue(request, 'db')
+        if marker.serialized_rollback:
+            request.getfixturevalue(request, 'serialized_rollback')
 
 
 @pytest.fixture(autouse=True, scope='class')
@@ -644,8 +646,9 @@ def validate_django_db(marker):
     It checks the signature and creates the `transaction` attribute on
     the marker which will have the correct value.
     """
-    def apifun(transaction=False):
+    def apifun(transaction=False, serialized_rollback=False):
         marker.transaction = transaction
+        marker.serialized_rollback = serialized_rollback
     apifun(*marker.args, **marker.kwargs)