def METHOD_NAME(self):
    """api returns error 400 if there are no username changes left"""
    response = self.client.get(self.link)
    self.assertEqual(response.status_code, 200)
    for i in range(response.json()["changes_left"]):
        self.user.set_username("NewName%s" % i, self.user)
    response = self.client.get(self.link)
    self.assertEqual(response.json()["changes_left"], 0)
    response = self.client.post(self.link, data={"username": "Pointless"})
    self.assertEqual(response.status_code, 400)
    self.assertEqual(
        response.json()["detail"], "You can't change your username now."
    )
    self.assertTrue(self.user.username != "Pointless")