text: from django.test import TestCase
  from django.contrib.auth import get_user_model
  
  from core import models
  
  
  def sample_user(email='test@email.com', password='testpass'):
      """Create a sample user"""
      return get_user_model().objects.create_user(email, password)
  
  
  class ModelTests(TestCase):
  
      def test_create_user_with_email_suxxeful(self):
          """Test creating new user with an email succeful"""
          email = 'test@london.org'
          password = 'Testpass123'
          user = get_user_model().objects.create_user(
              email=email,
              password=password
          )
          self.assertEqual(user.email, email)
          self.assertTrue(user.check_password(password))
  
      def test_new_user_email_normalized(self):
          """Test the email is normalized"""
          email = "test@LONDON.ORG"
          user = get_user_model().objects.create_user(email, 'test123')
          self.assertEqual(user.email, email.lower())
  
      def test_new_user_invalid_email(self):
          """Test creating user with no email raises error"""
          with self.assertRaises(ValueError):
              get_user_model().objects.create_user(None, 'test123')
  
      def test_create_new_superuser(self):
          """Test creating new superuser"""
          user = get_user_model().objects.create_superuser(
              'test@london.com',
              'test123')
          self.assertTrue(user.is_superuser)
          self.assertTrue(user.is_staff)
  
      def test_tag_str(self):
          """Test the tag string representatioin"""
          tag = models.Tag.objects.create(
              user=sample_user(),
              name='Vegan'
          )
          self.assertEqual(str(tag), tag.name)
  