Example Python test

test_login.py

from unittest import TestCase
from rest_framework import status
from rest_framework.test import APIClient


class BaseTestCase(TestCase):
    def setUp(self):
        self.client = APIClient()

    def post_login(self, username='johndoe', password='P@$$word'):
        return self.client.post('/api/auth/login', {'username': username, 'password': password})


class TestLogin(BaseTestCase):
    def test_successful_login(self):
        response = self.post_login()
        self.assertEqual(response.status, status.HTTP_200_OK)

    def test_missing_username_is_not_allowed(self):
        response = self.post_login(username='')
        self.assertEqual(response.status, status.HTTP_422_UNPROCESSABLE_ENTITY)
        self.assertIn(response.data['errors'], 'An username is required to log in.')

    def test_missing_password_is_not_allowed(self):
        response = self.post_login(password='')
        self.assertEqual(response.status, status.HTTP_422_UNPROCESSABLE_ENTITY)
        self.assertIn(response.data['errors'], 'A password is required to log in.')

    def test_username_with_special_chars_is_not_allowed(self):
        response = self.post_login(username='u$ern@me')
        self.assertIn(response.data['errors'], 'Special characters are not allowed on the username.')

Good work on the test. Done beyond expectations.

You could add some docstrings on each function and class

This was thorough and well thought.