home / skills / affaan-m / everything-claude-code / django-tdd
This skill guides you through Django TDD with pytest-django, factory_boy, and DRF testing to accelerate reliable API and model tests.
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---
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
```python
# Step 1: RED - Write failing test
def test_user_creation():
user = User.objects.create_user(email='[email protected]', password='testpass123')
assert user.email == '[email protected]'
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
```ini
# 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
```python
# 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
```python
# 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='[email protected]',
password='testpass123',
username='testuser'
)
@pytest.fixture
def admin_user(db):
"""Create an admin user."""
return User.objects.create_superuser(
email='[email protected]',
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
def authenticated_api_client(api_client, user):
"""Return authenticated API client."""
api_client.force_authenticate(user=user)
return api_client
```
## Factory Boy
### Factory Setup
```python
# 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(lambda obj: obj.name.lower().replace(' ', '-'))
description = factory.Faker('text')
price = fuzzy.FuzzyDecimal(10.00, 1000.00, 2)
stock = fuzzy.FuzzyInteger(0, 100)
is_active = True
category = factory.SubFactory(CategoryFactory)
created_by = factory.SubFactory(UserFactory)
@factory.post_generation
def tags(self, create, extracted, **kwargs):
"""Add tags to product."""
if not create:
return
if extracted:
for tag in extracted:
self.tags.add(tag)
```
### Using Factories
```python
# 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
```python
# 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='[email protected]')
assert user.email == '[email protected]'
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='[email protected]',
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='[email protected]')
assert str(user) == '[email protected]'
class TestProductModel:
"""Test Product model."""
def test_product_creation(self, db):
"""Test creating a product."""
product = ProductFactory()
assert product.id is not None
assert product.is_active is True
assert product.created_at is not None
def test_product_slug_generation(self, db):
"""Test automatic slug generation."""
product = ProductFactory(name='Test Product')
assert product.slug == 'test-product'
def test_product_price_validation(self, db):
"""Test price cannot be negative."""
product = ProductFactory(price=-10)
with pytest.raises(ValidationError):
product.full_clean()
def test_product_manager_active(self, db):
"""Test active manager method."""
ProductFactory.create_batch(5, is_active=True)
ProductFactory.create_batch(3, is_active=False)
active_count = Product.objects.active().count()
assert active_count == 5
def test_product_stock_management(self, db):
"""Test stock management."""
product = ProductFactory(stock=10)
product.reduce_stock(5)
product.refresh_from_db()
assert product.stock == 5
with pytest.raises(ValueError):
product.reduce_stock(10) # Not enough stock
```
## View Testing
### Django View Testing
```python
# 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):
"""Test product creation as authenticated user."""
response = authenticated_client.get(reverse('products:create'))
assert response.status_code == 200
def test_product_create_post(self, authenticated_client, db, category):
"""Test creating a product via POST."""
data = {
'name': 'Test Product',
'description': 'A test product',
'price': '99.99',
'stock': 10,
'category': category.id,
}
response = authenticated_client.post(reverse('products:create'), data)
assert response.status_code == 302
assert Product.objects.filter(name='Test Product').exists()
```
## DRF API Testing
### Serializer Testing
```python
# 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
def test_price_validation(self, db):
"""Test price validation."""
data = {
'name': 'Test Product',
'price': '-10.00',
'stock': 10,
}
serializer = ProductSerializer(data=data)
assert not serializer.is_valid()
assert 'price' in serializer.errors
def test_stock_validation(self, db):
"""Test stock cannot be negative."""
data = {
'name': 'Test Product',
'price': '99.99',
'stock': -5,
}
serializer = ProductSerializer(data=data)
assert not serializer.is_valid()
assert 'stock' in serializer.errors
```
### API ViewSet Testing
```python
# 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):
"""Test creating product without authentication."""
url = reverse('api:product-list')
data = {'name': 'Test Product', 'price': '99.99'}
response = api_client.post(url, data)
assert response.status_code == status.HTTP_401_UNAUTHORIZED
def test_create_product_authorized(self, authenticated_api_client, db):
"""Test creating product as authenticated user."""
url = reverse('api:product-list')
data = {
'name': 'Test Product',
'description': 'Test',
'price': '99.99',
'stock': 10,
}
response = authenticated_api_client.post(url, data)
assert response.status_code == status.HTTP_201_CREATED
assert response.data['name'] == 'Test Product'
def test_update_product(self, authenticated_api_client, db):
"""Test updating a product."""
product = ProductFactory(created_by=authenticated_api_client.user)
url = reverse('api:product-detail', kwargs={'pk': product.id})
data = {'name': 'Updated Product'}
response = authenticated_api_client.patch(url, data)
assert response.status_code == status.HTTP_200_OK
assert response.data['name'] == 'Updated Product'
def test_delete_product(self, authenticated_api_client, db):
"""Test deleting a product."""
product = ProductFactory(created_by=authenticated_api_client.user)
url = reverse('api:product-detail', kwargs={'pk': product.id})
response = authenticated_api_client.delete(url)
assert response.status_code == status.HTTP_204_NO_CONTENT
def test_filter_products_by_price(self, api_client, db):
"""Test filtering products by price."""
ProductFactory(price=50)
ProductFactory(price=150)
url = reverse('api:product-list')
response = api_client.get(url, {'price_min': 100})
assert response.status_code == status.HTTP_200_OK
assert response.data['count'] == 1
def test_search_products(self, api_client, db):
"""Test searching products."""
ProductFactory(name='Apple iPhone')
ProductFactory(name='Samsung Galaxy')
url = reverse('api:product-list')
response = api_client.get(url, {'search': 'Apple'})
assert response.status_code == status.HTTP_200_OK
assert response.data['count'] == 1
```
## Mocking and Patching
### Mocking External Services
```python
# 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 == 302
assert 'error' in response.url
```
### Mocking Email Sending
```python
# 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
```python
# 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': '[email protected]',
'password': 'testpass123',
'password_confirm': 'testpass123',
})
assert response.status_code == 302
# Step 2: Login
response = client.post(reverse('users:login'), {
'email': '[email protected]',
'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': 1,
})
assert response.status_code == 302
# Step 5: Checkout
response = client.get(reverse('checkout:review'))
assert response.status_code == 200
assert product.name in response.content.decode()
# Step 6: Complete purchase
with patch('apps.checkout.services.process_payment') as mock_payment:
mock_payment.return_value = True
response = client.post(reverse('checkout:complete'))
assert response.status_code == 302
assert Order.objects.filter(user__email='[email protected]').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
```bash
# 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.
This skill teaches test-driven development for Django projects using pytest-django, factory_boy, and tools for testing Django REST Framework APIs. It packages practical setup, fixtures, factories, and example tests to speed up building reliable model, view, serializer, and API tests. Follow the red-green-refactor workflow and the provided configs to get fast, repeatable tests with coverage and mocked external behavior.
The skill provides ready-to-use pytest configuration, test settings, and shared fixtures to run tests in-memory and skip migrations for speed. It includes factory_boy factories for models, example model/view/serializer/API tests, and patterns for authentication, API client use, and coverage reporting. Use the samples to adopt TDD: write a failing test, implement minimal code, then refactor while keeping tests green.
How do I speed up test runs?
Use in-memory SQLite, disable migrations, use MD5 password hasher, and run pytest with --reuse-db to avoid recreating the database each run.
When should I use factories vs fixtures?
Prefer factory_boy for reusable, composable test data and create fixtures for cross-cutting concerns like authenticated clients or timezone settings.