'makemigrations exits if a nonexistent app is specified.'

def test_makemigrations_no_app_sys_exit(self):

    err = io.StringIO()
    with self.assertRaises(SystemExit):
        call_command('makemigrations', 'this_app_does_not_exist', stderr=err)
    self.assertIn("'this_app_does_not_exist'    could    not    be    found.", err.getvalue())
