django-tdd

name	django-tdd
description	Django testing strategies with pytest-django, TDD methodology, factory_boy, mocking, coverage, and testing Django REST Framework APIs.

Django Testing with TDD

Test-driven development for Django applications using pytest, factory_boy, and Django REST Framework.

When to Activate

• Writing new Django applications
• Implementing Django REST Framework APIs
• Testing Django models, views, and serializers
• Setting up testing infrastructure for Django projects

TDD Workflow for Django

Red-Green-Refactor Cycle

# Step 1: RED - Write failing test
def test_user_creation():
    user = User.objects.create_user(email='[e-mail]', password='testpass123')
    assert user.email == '[e-mail]'
    assert user.check_password('testpass123')
    assert not user.is_staff

# Step 2: GREEN - Make test pass
# Create User model or factory

# Step 3: REFACTOR - Improve while keeping tests green

Setup

pytest Configuration

# pytest.ini
[pytest]
DJANGO_SETTINGS_MODULE = config.settings.test
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts =
    --reuse-db
    --nomigrations
    --cov=apps
    --cov-report=html
    --cov-report=term-missing
    --strict-markers
markers =
    slow: marks tests as slow
    integration: marks tests as integration tests

Test Settings

# config/settings/test.py
from .base import *

DEBUG = True
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': ':memory:',
    }
}

# Disable migrations for speed
class DisableMigrations:
    def __contains__(self, item):
        return True

    def __getitem__(self, item):
        return None

MIGRATION_MODULES = DisableMigrations()

# Faster password hashing
PASSWORD_HASHERS = [
    'django.contrib.auth.hashers.MD5PasswordHasher',
]

# Email backend
EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'

# Celery always eager
CELERY_TASK_ALWAYS_EAGER = True
CELERY_TASK_EAGER_PROPAGATES = True

conftest.py

# tests/conftest.py
import pytest
from django.utils import timezone
from django.contrib.auth import get_user_model

User = get_user_model()

@pytest.fixture(autouse=True)
def timezone_settings(settings):
    """Ensure consistent timezone."""
    settings.TIME_ZONE = 'UTC'

@pytest.fixture
def user(db):
    """Create a test user."""
    return User.objects.create_user(
        email='[e-mail]',
        password='testpass123',
        username='testuser'
    )

@pytest.fixture
def admin_user(db):
    """Create an admin user."""
    return User.objects.create_superuser(
        email='[e-mail]',
        password='adminpass123',
        username='admin'
    )

@pytest.fixture
def authenticated_client(client, user):
    """Return authenticated client."""
    client.force_login(user)
    return client

@pytest.fixture
def api_client():
    """Return DRF API client."""
    from rest_framework.test import APIClient
    return APIClient()

@pytest.fixture
 ():
    
    api_client.force_authenticate(user=user)
     api_client

Factory Boy

Factory Setup

# tests/factories.py
import factory
from factory import fuzzy
from datetime import datetime, timedelta
from django.contrib.auth import get_user_model
from apps.products.models import Product, Category

User = get_user_model()

class UserFactory(factory.django.DjangoModelFactory):
    """Factory for User model."""

    class Meta:
        model = User

    email = factory.Sequence(lambda n: f"user{n}@example.com")
    username = factory.Sequence(lambda n: f"user{n}")
    password = factory.PostGenerationMethodCall('set_password', 'testpass123')
    first_name = factory.Faker('first_name')
    last_name = factory.Faker('last_name')
    is_active = True

class CategoryFactory(factory.django.DjangoModelFactory):
    """Factory for Category model."""

    class Meta:
        model = Category

    name = factory.Faker('word')
    slug = factory.LazyAttribute(lambda obj: obj.name.lower())
    description = factory.Faker('text')

class ProductFactory(factory.django.DjangoModelFactory):
    """Factory for Product model."""

    class Meta:
        model = Product

    name = factory.Faker('sentence', nb_words=3)
    slug = factory.LazyAttribute( obj: obj.name.lower().replace(, ))
    description = factory.Faker()
    price = fuzzy.FuzzyDecimal(, , )
    stock = fuzzy.FuzzyInteger(, )
    is_active = 
    category = factory.SubFactory(CategoryFactory)
    created_by = factory.SubFactory(UserFactory)


     ():
        
          create:
            
         extracted:
             tag  extracted:
                .tags.add(tag)

Using Factories

# tests/test_models.py
import pytest
from tests.factories import ProductFactory, UserFactory

def test_product_creation():
    """Test product creation using factory."""
    product = ProductFactory(price=100.00, stock=50)
    assert product.price == 100.00
    assert product.stock == 50
    assert product.is_active is True

def test_product_with_tags():
    """Test product with tags."""
    tags = [TagFactory(name='electronics'), TagFactory(name='new')]
    product = ProductFactory(tags=tags)
    assert product.tags.count() == 2

def test_multiple_products():
    """Test creating multiple products."""
    products = ProductFactory.create_batch(10)
    assert len(products) == 10

Model Testing

Model Tests

# tests/test_models.py
import pytest
from django.core.exceptions import ValidationError
from tests.factories import UserFactory, ProductFactory

class TestUserModel:
    """Test User model."""

    def test_create_user(self, db):
        """Test creating a regular user."""
        user = UserFactory(email='[e-mail]')
        assert user.email == '[e-mail]'
        assert user.check_password('testpass123')
        assert not user.is_staff
        assert not user.is_superuser

    def test_create_superuser(self, db):
        """Test creating a superuser."""
        user = UserFactory(
            email='[e-mail]',
            is_staff=True,
            is_superuser=True
        )
        assert user.is_staff
        assert user.is_superuser

    def test_user_str(self, db):
        """Test user string representation."""
        user = UserFactory(email='[e-mail]')
        assert str(user) == '[e-mail]'

class TestProductModel:
    """Test Product model."""

    def test_product_creation():
        
        product = ProductFactory()
         product.   
         product.is_active  
         product.created_at   

     ():
        
        product = ProductFactory(name=)
         product.slug == 

     ():
        
        product = ProductFactory(price=-)
         pytest.raises(ValidationError):
            product.full_clean()

     ():
        
        ProductFactory.create_batch(, is_active=)
        ProductFactory.create_batch(, is_active=)

        active_count = Product.objects.active().count()
         active_count == 

     ():
        
        product = ProductFactory(stock=)
        product.reduce_stock()
        product.refresh_from_db()
         product.stock == 

         pytest.raises(ValueError):
            product.reduce_stock()  

View Testing

Django View Testing

# tests/test_views.py
import pytest
from django.urls import reverse
from tests.factories import ProductFactory, UserFactory

class TestProductViews:
    """Test product views."""

    def test_product_list(self, client, db):
        """Test product list view."""
        ProductFactory.create_batch(10)

        response = client.get(reverse('products:list'))

        assert response.status_code == 200
        assert len(response.context['products']) == 10

    def test_product_detail(self, client, db):
        """Test product detail view."""
        product = ProductFactory()

        response = client.get(reverse('products:detail', kwargs={'slug': product.slug}))

        assert response.status_code == 200
        assert response.context['product'] == product

    def test_product_create_requires_login(self, client, db):
        """Test product creation requires authentication."""
        response = client.get(reverse('products:create'))

        assert response.status_code == 302
        assert response.url.startswith('/accounts/login/')

    def test_product_create_authenticated(self, authenticated_client, db):
        
        response = authenticated_client.get(reverse())

         response.status_code == 

     ():
        
        data = {
            : ,
            : ,
            : ,
            : ,
            : category.,
        }

        response = authenticated_client.post(reverse(), data)

         response.status_code == 
         Product.objects.(name=).exists()

DRF API Testing

Serializer Testing

# tests/test_serializers.py
import pytest
from rest_framework.exceptions import ValidationError
from apps.products.serializers import ProductSerializer
from tests.factories import ProductFactory

class TestProductSerializer:
    """Test ProductSerializer."""

    def test_serialize_product(self, db):
        """Test serializing a product."""
        product = ProductFactory()
        serializer = ProductSerializer(product)

        data = serializer.data

        assert data['id'] == product.id
        assert data['name'] == product.name
        assert data['price'] == str(product.price)

    def test_deserialize_product(self, db):
        """Test deserializing product data."""
        data = {
            'name': 'Test Product',
            'description': 'Test description',
            'price': '99.99',
            'stock': 10,
            'category': 1,
        }

        serializer = ProductSerializer(data=data)

        assert serializer.is_valid()
        product = serializer.save()

        assert product.name == 'Test Product'
        assert float(product.price) == 99.99

     ():
        
        data = {
            : ,
            : ,
            : ,
        }

        serializer = ProductSerializer(data=data)

          serializer.is_valid()
           serializer.errors

     ():
        
        data = {
            : ,
            : ,
            : -,
        }

        serializer = ProductSerializer(data=data)

          serializer.is_valid()
           serializer.errors

API ViewSet Testing

# tests/test_api.py
import pytest
from rest_framework.test import APIClient
from rest_framework import status
from django.urls import reverse
from tests.factories import ProductFactory, UserFactory

class TestProductAPI:
    """Test Product API endpoints."""

    @pytest.fixture
    def api_client(self):
        """Return API client."""
        return APIClient()

    def test_list_products(self, api_client, db):
        """Test listing products."""
        ProductFactory.create_batch(10)

        url = reverse('api:product-list')
        response = api_client.get(url)

        assert response.status_code == status.HTTP_200_OK
        assert response.data['count'] == 10

    def test_retrieve_product(self, api_client, db):
        """Test retrieving a product."""
        product = ProductFactory()

        url = reverse('api:product-detail', kwargs={'pk': product.id})
        response = api_client.get(url)

        assert response.status_code == status.HTTP_200_OK
        assert response.data['id'] == product.id

    def test_create_product_unauthorized(self, api_client, db):
        
        url = reverse()
        data = {: , : }

        response = api_client.post(url, data)

         response.status_code == status.HTTP_401_UNAUTHORIZED

     ():
        
        url = reverse()
        data = {
            : ,
            : ,
            : ,
            : ,
        }

        response = authenticated_api_client.post(url, data)

         response.status_code == status.HTTP_201_CREATED
         response.data[] == 

     ():
        
        product = ProductFactory(created_by=authenticated_api_client.user)

        url = reverse(, kwargs={: product.})
        data = {: }

        response = authenticated_api_client.patch(url, data)

         response.status_code == status.HTTP_200_OK
         response.data[] == 

     ():
        
        product = ProductFactory(created_by=authenticated_api_client.user)

        url = reverse(, kwargs={: product.})
        response = authenticated_api_client.delete(url)

         response.status_code == status.HTTP_204_NO_CONTENT

     ():
        
        ProductFactory(price=)
        ProductFactory(price=)

        url = reverse()
        response = api_client.get(url, {: })

         response.status_code == status.HTTP_200_OK
         response.data[] == 

     ():
        
        ProductFactory(name=)
        ProductFactory(name=)

        url = reverse()
        response = api_client.get(url, {: })

         response.status_code == status.HTTP_200_OK
         response.data[] == 

Mocking and Patching

Mocking External Services

# tests/test_views.py
from unittest.mock import patch, Mock
import pytest

class TestPaymentView:
    """Test payment view with mocked payment gateway."""

    @patch('apps.payments.services.stripe')
    def test_successful_payment(self, mock_stripe, client, user, product):
        """Test successful payment with mocked Stripe."""
        # Configure mock
        mock_stripe.Charge.create.return_value = {
            'id': 'ch_123',
            'status': 'succeeded',
            'amount': 9999,
        }

        client.force_login(user)
        response = client.post(reverse('payments:process'), {
            'product_id': product.id,
            'token': 'tok_visa',
        })

        assert response.status_code == 302
        mock_stripe.Charge.create.assert_called_once()

    @patch('apps.payments.services.stripe')
    def test_failed_payment(self, mock_stripe, client, user, product):
        """Test failed payment."""
        mock_stripe.Charge.create.side_effect = Exception('Card declined')

        client.force_login(user)
        response = client.post(reverse('payments:process'), {
            'product_id': product.id,
            'token': 'tok_visa',
        })

        assert response.status_code == 
           response.url

Mocking Email Sending

# tests/test_email.py
from django.core import mail
from django.test import override_settings

@override_settings(EMAIL_BACKEND='django.core.mail.backends.locmem.EmailBackend')
def test_order_confirmation_email(db, order):
    """Test order confirmation email."""
    order.send_confirmation_email()

    assert len(mail.outbox) == 1
    assert order.user.email in mail.outbox[0].to
    assert 'Order Confirmation' in mail.outbox[0].subject

Integration Testing

Full Flow Testing

# tests/test_integration.py
import pytest
from django.urls import reverse
from tests.factories import UserFactory, ProductFactory

class TestCheckoutFlow:
    """Test complete checkout flow."""

    def test_guest_to_purchase_flow(self, client, db):
        """Test complete flow from guest to purchase."""
        # Step 1: Register
        response = client.post(reverse('users:register'), {
            'email': '[e-mail]',
            'password': 'testpass123',
            'password_confirm': 'testpass123',
        })
        assert response.status_code == 302

        # Step 2: Login
        response = client.post(reverse('users:login'), {
            'email': '[e-mail]',
            'password': 'testpass123',
        })
        assert response.status_code == 302

        # Step 3: Browse products
        product = ProductFactory(price=100)
        response = client.get(reverse('products:detail', kwargs={'slug': product.slug}))
        assert response.status_code == 200

        # Step 4: Add to cart
        response = client.post(reverse('cart:add'), {
            'product_id': product.id,
            'quantity': ,
        })
         response.status_code == 

        
        response = client.get(reverse())
         response.status_code == 
         product.name  response.content.decode()

        
         patch()  mock_payment:
            mock_payment.return_value = 
            response = client.post(reverse())

         response.status_code == 
         Order.objects.(user__email=).exists()

Testing Best Practices

DO

• Use factories: Instead of manual object creation
• One assertion per test: Keep tests focused
• Descriptive test names: test_user_cannot_delete_others_post
• Test edge cases: Empty inputs, None values, boundary conditions
• Mock external services: Don't depend on external APIs
• Use fixtures: Eliminate duplication
• Test permissions: Ensure authorization works
• Keep tests fast: Use --reuse-db and --nomigrations

DON'T

• Don't test Django internals: Trust Django to work
• Don't test third-party code: Trust libraries to work
• Don't ignore failing tests: All tests must pass
• Don't make tests dependent: Tests should run in any order
• Don't over-mock: Mock only external dependencies
• Don't test private methods: Test public interface
• Don't use production database: Always use test database

Coverage

Coverage Configuration

# Run tests with coverage
pytest --cov=apps --cov-report=html --cov-report=term-missing

# Generate HTML report
open htmlcov/index.html

Coverage Goals

Component	Target Coverage
Models	90%+
Serializers	85%+
Views	80%+
Services	90%+
Utilities	80%+
Overall	80%+

Quick Reference

Pattern	Usage
@pytest.mark.django_db	Enable database access
client	Django test client
api_client	DRF API client
factory.create_batch(n)	Create multiple objects
patch('module.function')	Mock external dependencies
override_settings	Temporarily change settings
force_authenticate()	Bypass authentication in tests
assertRedirects	Check for redirects
assertTemplateUsed	Verify template usage
mail.outbox	Check sent emails

Remember: Tests are documentation. Good tests explain how your code should work. Keep them simple, readable, and maintainable.