old_contents: from django.test import TestCase
  
  from ..backends import CaseInsensitiveEmailBackend
  from .factories import UserFactory
  
  
  class CaseInsensitveEmailBackendTest(TestCase):
      def test_authenticate(self):
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          user = UserFactory.create(email=email, password=password, is_active=True)
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(
              username='Test-email@example.com', password=password)
  
          self.assertEqual(user, authenticated_user)
  
      def test_authenticate_no_username(self):
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          user = UserFactory.create(email=email, password=password, is_active=True)
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(
              email='Test-email@example.com', password=password)
  
          self.assertEqual(user, authenticated_user)
  
      def test_authenticate_no_user(self):
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(email=email, password=password)
  
          self.assertIs(authenticated_user, None)
  
new_contents: from django.test import TestCase
  
  from ..backends import CaseInsensitiveEmailBackend
  from .factories import UserFactory
  
  
  class CaseInsensitveEmailBackendTest(TestCase):
      def test_authenticate(self):
          """
          Check case-insensitive username authentication
          """
  
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          user = UserFactory.create(email=email, password=password, is_active=True)
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(
              username='Test-email@example.com', password=password)
  
          self.assertEqual(user, authenticated_user)
  
      def test_authenticate_no_username(self):
          """
          Passing USERNAME_FIELD to authenticate is valid
          """
  
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          user = UserFactory.create(email=email, password=password, is_active=True)
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(
              email='Test-email@example.com', password=password)
  
          self.assertEqual(user, authenticated_user)
  
      def test_authenticate_no_user(self):
          """
          If no username is provided, just return None
          """
  
          email = 'test-Email@example.com'
          password = 'arandomsuperstrongpassword'
  
          backend = CaseInsensitiveEmailBackend()
          authenticated_user = backend.authenticate(email=email, password=password)
  
          self.assertIs(authenticated_user, None)
  
subject: Add docstrings to test_backends