def METHOD_NAME(self):
    newdata = preferences.load_file(self.base.paths.preferences)
    newdata["controller"]["landing_tab"] = 2
    preferences.save_file(self.base.paths.preferences, newdata)
    data = preferences.load_file(self.base.paths.preferences)
    self.assertEqual(data["controller"]["landing_tab"], 2, "Could not write to preferences file")