Run tests in the same order as Django

This uses `pytest_collection_modifyitems` to order the tests.

Fixes #214.

Author: blueyed

pytest_django/plugin.py

@@ -189,13 +189,13 @@ def pytest_load_initial_conftests(early_config, parser, args):
     early_config.addinivalue_line(
         'markers',
         'django_db(transaction=False): Mark the test as using '
-        'the django test database.  The *transaction* argument marks will '
-        "allow you to use real transactions in the test like Django's "
+        'the Django test database.  The *transaction* argument '
+        "allows you to use real transactions in the test like with Django's "
         'TransactionTestCase.')
     early_config.addinivalue_line(
         'markers',
         'urls(modstr): Use a different URLconf for this test, similar to '
-        'the `urls` attribute of Django `TestCase` objects.  *modstr* is '
+        "the `urls` attribute of Django's `TestCase` objects.  *modstr* is "
         'a string specifying the module of a URL config, e.g. '
         '"my_app.test_urls".')
     early_config.addinivalue_line(
@@ -352,6 +352,34 @@ def pytest_runtest_setup(item):
         _disable_class_methods(cls)
 
 
+def pytest_collection_modifyitems(session, config, items):
+    def get_marker_transaction(test):
+        marker = test.get_marker("django_db")
+        if marker:
+            validate_django_db(marker)
+            return marker.transaction
+        return None
+
+    def has_fixture(test, fixture):
+        funcargnames = getattr(test, 'funcargnames', None)
+        return funcargnames and fixture in funcargnames
+
+    def get_order_number(test):
+        if get_marker_transaction(test) is True:
+            return 1
+        if has_fixture(test, 'transactional_db'):
+            return 1
+
+        if get_marker_transaction(test) is False:
+            return 0
+        if has_fixture(test, 'db'):
+            return 0
+
+        return 2
+
+    items[:] = sorted(items, key=get_order_number)
+
+
 @pytest.fixture(autouse=True, scope='session')
 def django_test_environment(request):
     """

tests/test_db_setup.py

@@ -25,6 +25,38 @@ def test_db_can_be_accessed():
     ])
 
 
+def test_db_order(django_testdir):
+    """Test order in which tests are being executed."""
+
+    django_testdir.create_test_module('''
+        import pytest
+
+        from .app.models import Item
+
+        @pytest.mark.django_db(transaction=True)
+        def test_run_second_decorator():
+            pass
+
+        def test_run_second_fixture(transactional_db):
+            pass
+
+        def test_run_first_fixture(db):
+            pass
+
+        @pytest.mark.django_db
+        def test_run_first_decorator():
+            pass
+    ''')
+    result = django_testdir.runpytest_subprocess('-v', '-s')
+    assert result.ret == 0
+    result.stdout.fnmatch_lines([
+        "*test_run_first_fixture*",
+        "*test_run_first_decorator*",
+        "*test_run_second_decorator*",
+        "*test_run_second_fixture*",
+    ])
+
+
 def test_db_reuse(django_testdir):
     """
     Test the re-use db functionality.