Handle south migrations

[blueyed]

Ref: #128

[pelme]

Looks good.

Just having SOUTH_TESTS_MIGRATE = False makes it behave as before, right?

[blueyed]

Unfortunately it's not fine.

With --create-db it fails (--reuse-db is fine, given that the DB is OK).

The initial problem is with (e.g.) socialaccount_socialapp, or any other app using migrations:

request = <SubRequest '_django_db_setup' for <Function 'test_no_change_permission'>>, _django_test_environment = None
_django_cursor_wrapper = <pytest_django.plugin.CursorManager object at 0x3d04a10>

    @pytest.fixture(scope='session')
    def _django_db_setup(request,
                         _django_test_environment,
                         _django_cursor_wrapper):
        """Session-wide database setup, internal to pytest-django"""
        skip_if_no_django()

        from .compat import setup_databases, teardown_databases

        # xdist
        if hasattr(request.config, 'slaveinput'):
            db_suffix = request.config.slaveinput['slaveid']
        else:
            db_suffix = None

        monkey_patch_creation_for_db_suffix(db_suffix)

        with _django_cursor_wrapper:
            # Monkey patch Django's setup code to support database re-use
            if request.config.getvalue('reuse_db'):
                if not request.config.getvalue('create_db'):
                    monkey_patch_creation_for_db_reuse()

            # Create the database
>           db_cfg = setup_databases(verbosity=0, interactive=False)

…/pytest_django/pytest_django/fixtures.py:47:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
…/django-stable/django/test/runner.py:279: in setup_databases
    verbosity, autoclobber=not interactive)
…/django-stable/django/db/backends/creation.py:349: in create_test_db
    database=self.connection.alias)
…/django-stable/django/core/management/__init__.py:159: in call_command
    return klass.execute(*args, **defaults)
…/django-stable/django/core/management/base.py:285: in execute
    output = self.handle(*args, **options)
…/django-stable/django/core/management/base.py:415: in handle
    return self.handle_noargs(**options)
…/django-stable/django/core/management/commands/flush.py:78: in handle_noargs
    six.reraise(CommandError, CommandError(new_msg), sys.exc_info()[2])
…/django-stable/django/core/management/commands/flush.py:69: in handle_noargs
    cursor.execute(sql)
…/django-stable/django/db/backends/util.py:53: in execute
    return self.cursor.execute(sql, params)
…/django-stable/django/db/utils.py:99: in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)

…

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <django.db.backends.util.CursorWrapper object at 0x4890390>, sql = 'SELECT setval(pg_get_serial_sequence(\'"socialaccount_socialapp"\',\'id\'), 1, false);'
params = None

    def execute(self, sql, params=None):
        self.db.validate_no_broken_transaction()
        self.db.set_dirty()
        with self.db.wrap_database_errors:
            if params is None:
>               return self.cursor.execute(sql)
E               CommandError: Database tmm_tests couldn't be flushed. Possible reasons:
E                 * The database isn't running or isn't configured correctly.
E                 * At least one of the expected database tables doesn't exist.
E                 * The SQL was invalid.
E               Hint: Look at the output of 'django-admin.py sqlflush'. That's the SQL this command wasn't able to run.
E               The full error: relation "socialaccount_socialapp" does not exist

…/django-stable/django/db/backends/util.py:51: CommandError
------------------------------------------------------------------------- Captured stderr setup --------------------------------------------------------------------------
Got an error creating the test database: database "tmm_tests" already exists

The following tests then fail with:

Got an error recreating the test database: cannot drop the currently open database

       …
       except Exception as e:
            sys.stderr.write(
                "Got an error creating the test database: %s\n" % e)
            if not autoclobber:
                confirm = input(
                    "Type 'yes' if you would like to try deleting the test "
                    "database '%s', or 'no' to cancel: " % test_database_name)
            if autoclobber or confirm == 'yes':
                try:
                    if verbosity >= 1:
                        print("Destroying old test database '%s'..."
                              % self.connection.alias)
                    cursor.execute(
                        "DROP DATABASE %s" % qn(test_database_name))
                    cursor.execute(
                        "CREATE DATABASE %s %s" % (qn(test_database_name),
                                                   suffix))
                except Exception as e:
                    sys.stderr.write(
                        "Got an error recreating the test database: %s\n" % e)
>                   sys.exit(2)
E                   SystemExit: 2

…/django-stable/django/db/backends/creation.py:411: SystemExit
--- … Captured stderr setup … ---
Got an error creating the test database: database "project_tests" already exists

Got an error recreating the test database: cannot drop the currently open database

[blueyed]

I've pushed a new commit, which fixes this and also fixes handling of initial_data.

[blueyed]

@pelme
This should be good to merge, but please review it first.

I am skipping the South related tests for Python 3.4 and Django >= 1.7, because South appears to cause trouble with both.

[pelme]

Thank you so much for this!