How to use the djet.utils.refresh function in djet

def test_post_should_not_set_new_username_if_invalid(self):
        user = create_user()
        data = {
            'new_username': '$ wrong username #',
            'current_password': 'secret',
        }
        request = self.factory.post(user=user, data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_400_BAD_REQUEST)
        user = utils.refresh(user)
        self.assertNotEqual(user.username, data['new_username'])

def test_post_should_set_new_username(self):
        user = create_user()
        data = {
            'new_username': 'ringo',
            'current_password': 'secret',
        }
        request = self.factory.post(user=user, data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_204_NO_CONTENT)
        user = utils.refresh(user)
        self.assertEqual(data['new_username'], user.username)

def test_post_should_not_set_new_username_if_exists(self):
        username = 'tom'
        create_user(username=username)
        user = create_user(username='john')
        data = {
            'new_username': username,
            'current_password': 'secret',
        }
        request = self.factory.post(user=user, data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_400_BAD_REQUEST)
        user = utils.refresh(user)
        self.assertNotEqual(user.username, username)

def test_post_should_activate_user_and_not_login(self):
        user = create_user()
        user.is_active = False
        user.save()
        data = {
            'uid': djoser.utils.encode_uid(user.pk),
            'token': default_token_generator.make_token(user),
        }
        request = self.factory.post(data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_204_NO_CONTENT)
        user = utils.refresh(user)
        self.assertTrue(user.is_active)

def test_post_should_not_set_new_username_if_exists(self):
        username = 'tom'
        create_user(username=username)
        user = create_user(username='john')
        data = {
            'new_username': username,
            'current_password': 'secret',
        }
        request = self.factory.post(user=user, data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_400_BAD_REQUEST)
        user = utils.refresh(user)
        self.assertNotEqual(user.username, username)

def test_post_should_set_new_password(self):
        user = create_user()
        data = {
            'uid': djoser.utils.encode_uid(user.pk),
            'token': default_token_generator.make_token(user),
            'new_password': 'new password',
        }

        request = self.factory.post(data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_204_NO_CONTENT)
        user = utils.refresh(user)
        self.assertTrue(user.check_password(data['new_password']))

def test_post_should_activate_user_and_not_login(self):
        user = create_user()
        user.is_active = False
        user.save()
        data = {
            'uid': djoser.utils.encode_uid(user.pk),
            'token': default_token_generator.make_token(user),
        }
        request = self.factory.post(data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_204_NO_CONTENT)
        user = utils.refresh(user)
        self.assertTrue(user.is_active)

def test_post_should_not_set_new_password_if_wrong_token(self):
        user = create_user()
        data = {
            'uid': djoser.utils.encode_uid(user.pk),
            'token': 'wrong-token',
            'new_password': 'new password',
        }
        request = self.factory.post(data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_400_BAD_REQUEST)
        self.assertEqual(response.data['non_field_errors'], [djoser.constants.INVALID_TOKEN_ERROR])
        user = utils.refresh(user)
        self.assertFalse(user.check_password(data['new_password']))

def test_post_should_not_set_new_password_if_mismatch(self):
        user = create_user()
        data = {
            'uid': djoser.utils.encode_uid(user.pk),
            'token': default_token_generator.make_token(user),
            'new_password': 'new password',
            're_new_password': 'wrong',
        }

        request = self.factory.post(data=data)

        response = self.view(request)

        self.assert_status_equal(response, status.HTTP_400_BAD_REQUEST)
        user = utils.refresh(user)
        self.assertFalse(user.check_password(data['new_password']))