730 lines
20 KiB
Markdown
730 lines
20 KiB
Markdown
---
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name: django-tdd
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description: Django testing strategies with pytest-django, TDD methodology, factory_boy, mocking, coverage, and testing Django REST Framework APIs.
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origin: ECC
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---
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# Django Testing with TDD
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Test-driven development for Django applications using pytest, factory_boy, and Django REST Framework.
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## When to Activate
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- Writing new Django applications
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- Implementing Django REST Framework APIs
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- Testing Django models, views, and serializers
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- Setting up testing infrastructure for Django projects
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## TDD Workflow for Django
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### Red-Green-Refactor Cycle
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```python
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# Step 1: RED - Write failing test
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def test_user_creation():
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user = User.objects.create_user(email='test@example.com', password='testpass123')
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assert user.email == 'test@example.com'
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assert user.check_password('testpass123')
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assert not user.is_staff
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# Step 2: GREEN - Make test pass
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# Create User model or factory
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# Step 3: REFACTOR - Improve while keeping tests green
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```
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## Setup
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### pytest Configuration
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```ini
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# pytest.ini
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[pytest]
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DJANGO_SETTINGS_MODULE = config.settings.test
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testpaths = tests
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python_files = test_*.py
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python_classes = Test*
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python_functions = test_*
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addopts =
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--reuse-db
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--nomigrations
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--cov=apps
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--cov-report=html
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--cov-report=term-missing
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--strict-markers
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markers =
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slow: marks tests as slow
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integration: marks tests as integration tests
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```
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### Test Settings
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```python
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# config/settings/test.py
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from .base import *
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DEBUG = True
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DATABASES = {
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'default': {
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'ENGINE': 'django.db.backends.sqlite3',
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'NAME': ':memory:',
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}
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}
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# Disable migrations for speed
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class DisableMigrations:
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def __contains__(self, item):
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return True
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def __getitem__(self, item):
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return None
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MIGRATION_MODULES = DisableMigrations()
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# Faster password hashing
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PASSWORD_HASHERS = [
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'django.contrib.auth.hashers.MD5PasswordHasher',
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]
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# Email backend
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EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
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# Celery always eager
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CELERY_TASK_ALWAYS_EAGER = True
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CELERY_TASK_EAGER_PROPAGATES = True
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```
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### conftest.py
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```python
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# tests/conftest.py
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import pytest
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from django.utils import timezone
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from django.contrib.auth import get_user_model
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User = get_user_model()
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@pytest.fixture(autouse=True)
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def timezone_settings(settings):
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"""Ensure consistent timezone."""
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settings.TIME_ZONE = 'UTC'
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@pytest.fixture
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def user(db):
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"""Create a test user."""
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return User.objects.create_user(
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email='test@example.com',
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password='testpass123',
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username='testuser'
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)
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@pytest.fixture
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def admin_user(db):
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"""Create an admin user."""
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return User.objects.create_superuser(
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email='admin@example.com',
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password='adminpass123',
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username='admin'
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)
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@pytest.fixture
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def authenticated_client(client, user):
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"""Return authenticated client."""
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client.force_login(user)
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return client
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@pytest.fixture
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def api_client():
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"""Return DRF API client."""
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from rest_framework.test import APIClient
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return APIClient()
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@pytest.fixture
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def authenticated_api_client(api_client, user):
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"""Return authenticated API client."""
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api_client.force_authenticate(user=user)
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return api_client
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```
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## Factory Boy
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### Factory Setup
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```python
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# tests/factories.py
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import factory
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from factory import fuzzy
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from datetime import datetime, timedelta
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from django.contrib.auth import get_user_model
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from apps.products.models import Product, Category
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User = get_user_model()
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class UserFactory(factory.django.DjangoModelFactory):
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"""Factory for User model."""
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class Meta:
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model = User
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email = factory.Sequence(lambda n: f"user{n}@example.com")
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username = factory.Sequence(lambda n: f"user{n}")
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password = factory.PostGenerationMethodCall('set_password', 'testpass123')
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first_name = factory.Faker('first_name')
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last_name = factory.Faker('last_name')
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is_active = True
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class CategoryFactory(factory.django.DjangoModelFactory):
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"""Factory for Category model."""
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class Meta:
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model = Category
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name = factory.Faker('word')
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slug = factory.LazyAttribute(lambda obj: obj.name.lower())
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description = factory.Faker('text')
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class ProductFactory(factory.django.DjangoModelFactory):
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"""Factory for Product model."""
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class Meta:
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model = Product
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name = factory.Faker('sentence', nb_words=3)
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slug = factory.LazyAttribute(lambda obj: obj.name.lower().replace(' ', '-'))
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description = factory.Faker('text')
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price = fuzzy.FuzzyDecimal(10.00, 1000.00, 2)
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stock = fuzzy.FuzzyInteger(0, 100)
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is_active = True
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category = factory.SubFactory(CategoryFactory)
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created_by = factory.SubFactory(UserFactory)
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@factory.post_generation
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def tags(self, create, extracted, **kwargs):
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"""Add tags to product."""
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if not create:
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return
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if extracted:
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for tag in extracted:
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self.tags.add(tag)
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```
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### Using Factories
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```python
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# tests/test_models.py
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import pytest
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from tests.factories import ProductFactory, UserFactory
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def test_product_creation():
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"""Test product creation using factory."""
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product = ProductFactory(price=100.00, stock=50)
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assert product.price == 100.00
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assert product.stock == 50
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assert product.is_active is True
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def test_product_with_tags():
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"""Test product with tags."""
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tags = [TagFactory(name='electronics'), TagFactory(name='new')]
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product = ProductFactory(tags=tags)
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assert product.tags.count() == 2
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def test_multiple_products():
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"""Test creating multiple products."""
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products = ProductFactory.create_batch(10)
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assert len(products) == 10
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```
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## Model Testing
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### Model Tests
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```python
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# tests/test_models.py
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import pytest
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from django.core.exceptions import ValidationError
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from tests.factories import UserFactory, ProductFactory
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class TestUserModel:
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"""Test User model."""
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def test_create_user(self, db):
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"""Test creating a regular user."""
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user = UserFactory(email='test@example.com')
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assert user.email == 'test@example.com'
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assert user.check_password('testpass123')
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assert not user.is_staff
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assert not user.is_superuser
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def test_create_superuser(self, db):
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"""Test creating a superuser."""
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user = UserFactory(
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email='admin@example.com',
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is_staff=True,
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is_superuser=True
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)
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assert user.is_staff
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assert user.is_superuser
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def test_user_str(self, db):
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"""Test user string representation."""
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user = UserFactory(email='test@example.com')
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assert str(user) == 'test@example.com'
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class TestProductModel:
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"""Test Product model."""
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def test_product_creation(self, db):
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"""Test creating a product."""
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product = ProductFactory()
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assert product.id is not None
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assert product.is_active is True
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assert product.created_at is not None
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def test_product_slug_generation(self, db):
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"""Test automatic slug generation."""
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product = ProductFactory(name='Test Product')
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assert product.slug == 'test-product'
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def test_product_price_validation(self, db):
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"""Test price cannot be negative."""
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product = ProductFactory(price=-10)
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with pytest.raises(ValidationError):
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product.full_clean()
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def test_product_manager_active(self, db):
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"""Test active manager method."""
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ProductFactory.create_batch(5, is_active=True)
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ProductFactory.create_batch(3, is_active=False)
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active_count = Product.objects.active().count()
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assert active_count == 5
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def test_product_stock_management(self, db):
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"""Test stock management."""
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product = ProductFactory(stock=10)
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product.reduce_stock(5)
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product.refresh_from_db()
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assert product.stock == 5
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with pytest.raises(ValueError):
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product.reduce_stock(10) # Not enough stock
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```
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## View Testing
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### Django View Testing
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```python
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# tests/test_views.py
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import pytest
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from django.urls import reverse
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from tests.factories import ProductFactory, UserFactory
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class TestProductViews:
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"""Test product views."""
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def test_product_list(self, client, db):
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"""Test product list view."""
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ProductFactory.create_batch(10)
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response = client.get(reverse('products:list'))
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assert response.status_code == 200
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assert len(response.context['products']) == 10
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def test_product_detail(self, client, db):
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"""Test product detail view."""
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product = ProductFactory()
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response = client.get(reverse('products:detail', kwargs={'slug': product.slug}))
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assert response.status_code == 200
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assert response.context['product'] == product
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def test_product_create_requires_login(self, client, db):
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"""Test product creation requires authentication."""
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response = client.get(reverse('products:create'))
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assert response.status_code == 302
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assert response.url.startswith('/accounts/login/')
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def test_product_create_authenticated(self, authenticated_client, db):
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"""Test product creation as authenticated user."""
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response = authenticated_client.get(reverse('products:create'))
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assert response.status_code == 200
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def test_product_create_post(self, authenticated_client, db, category):
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"""Test creating a product via POST."""
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data = {
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'name': 'Test Product',
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'description': 'A test product',
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'price': '99.99',
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'stock': 10,
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'category': category.id,
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}
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response = authenticated_client.post(reverse('products:create'), data)
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assert response.status_code == 302
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assert Product.objects.filter(name='Test Product').exists()
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```
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## DRF API Testing
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### Serializer Testing
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```python
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# tests/test_serializers.py
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import pytest
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from rest_framework.exceptions import ValidationError
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from apps.products.serializers import ProductSerializer
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from tests.factories import ProductFactory
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class TestProductSerializer:
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"""Test ProductSerializer."""
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def test_serialize_product(self, db):
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"""Test serializing a product."""
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product = ProductFactory()
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serializer = ProductSerializer(product)
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data = serializer.data
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assert data['id'] == product.id
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assert data['name'] == product.name
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assert data['price'] == str(product.price)
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def test_deserialize_product(self, db):
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"""Test deserializing product data."""
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data = {
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'name': 'Test Product',
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'description': 'Test description',
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'price': '99.99',
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'stock': 10,
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'category': 1,
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}
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serializer = ProductSerializer(data=data)
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assert serializer.is_valid()
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product = serializer.save()
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assert product.name == 'Test Product'
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assert float(product.price) == 99.99
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def test_price_validation(self, db):
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"""Test price validation."""
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data = {
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'name': 'Test Product',
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'price': '-10.00',
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'stock': 10,
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}
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serializer = ProductSerializer(data=data)
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assert not serializer.is_valid()
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assert 'price' in serializer.errors
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def test_stock_validation(self, db):
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"""Test stock cannot be negative."""
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data = {
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'name': 'Test Product',
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'price': '99.99',
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'stock': -5,
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}
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serializer = ProductSerializer(data=data)
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assert not serializer.is_valid()
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assert 'stock' in serializer.errors
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```
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### API ViewSet Testing
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```python
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# tests/test_api.py
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import pytest
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from rest_framework.test import APIClient
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from rest_framework import status
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from django.urls import reverse
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from tests.factories import ProductFactory, UserFactory
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class TestProductAPI:
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"""Test Product API endpoints."""
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@pytest.fixture
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def api_client(self):
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"""Return API client."""
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return APIClient()
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def test_list_products(self, api_client, db):
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"""Test listing products."""
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ProductFactory.create_batch(10)
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url = reverse('api:product-list')
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response = api_client.get(url)
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assert response.status_code == status.HTTP_200_OK
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assert response.data['count'] == 10
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def test_retrieve_product(self, api_client, db):
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"""Test retrieving a product."""
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product = ProductFactory()
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url = reverse('api:product-detail', kwargs={'pk': product.id})
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response = api_client.get(url)
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assert response.status_code == status.HTTP_200_OK
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assert response.data['id'] == product.id
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def test_create_product_unauthorized(self, api_client, db):
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"""Test creating product without authentication."""
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url = reverse('api:product-list')
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data = {'name': 'Test Product', 'price': '99.99'}
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response = api_client.post(url, data)
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assert response.status_code == status.HTTP_401_UNAUTHORIZED
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def test_create_product_authorized(self, authenticated_api_client, db):
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"""Test creating product as authenticated user."""
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url = reverse('api:product-list')
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data = {
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'name': 'Test Product',
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'description': 'Test',
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'price': '99.99',
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'stock': 10,
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}
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response = authenticated_api_client.post(url, data)
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assert response.status_code == status.HTTP_201_CREATED
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assert response.data['name'] == 'Test Product'
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def test_update_product(self, authenticated_api_client, db):
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"""Test updating a product."""
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product = ProductFactory(created_by=authenticated_api_client.user)
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url = reverse('api:product-detail', kwargs={'pk': product.id})
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data = {'name': 'Updated Product'}
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response = authenticated_api_client.patch(url, data)
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assert response.status_code == status.HTTP_200_OK
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assert response.data['name'] == 'Updated Product'
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def test_delete_product(self, authenticated_api_client, db):
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"""Test deleting a product."""
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product = ProductFactory(created_by=authenticated_api_client.user)
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url = reverse('api:product-detail', kwargs={'pk': product.id})
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response = authenticated_api_client.delete(url)
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assert response.status_code == status.HTTP_204_NO_CONTENT
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def test_filter_products_by_price(self, api_client, db):
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"""Test filtering products by price."""
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ProductFactory(price=50)
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ProductFactory(price=150)
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url = reverse('api:product-list')
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response = api_client.get(url, {'price_min': 100})
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assert response.status_code == status.HTTP_200_OK
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assert response.data['count'] == 1
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def test_search_products(self, api_client, db):
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"""Test searching products."""
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ProductFactory(name='Apple iPhone')
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ProductFactory(name='Samsung Galaxy')
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url = reverse('api:product-list')
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response = api_client.get(url, {'search': 'Apple'})
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assert response.status_code == status.HTTP_200_OK
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assert response.data['count'] == 1
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```
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## Mocking and Patching
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### Mocking External Services
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```python
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# tests/test_views.py
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from unittest.mock import patch, Mock
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import pytest
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class TestPaymentView:
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"""Test payment view with mocked payment gateway."""
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@patch('apps.payments.services.stripe')
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def test_successful_payment(self, mock_stripe, client, user, product):
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"""Test successful payment with mocked Stripe."""
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# Configure mock
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mock_stripe.Charge.create.return_value = {
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'id': 'ch_123',
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'status': 'succeeded',
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'amount': 9999,
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}
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client.force_login(user)
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response = client.post(reverse('payments:process'), {
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'product_id': product.id,
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'token': 'tok_visa',
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})
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assert response.status_code == 302
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mock_stripe.Charge.create.assert_called_once()
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@patch('apps.payments.services.stripe')
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def test_failed_payment(self, mock_stripe, client, user, product):
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"""Test failed payment."""
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mock_stripe.Charge.create.side_effect = Exception('Card declined')
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client.force_login(user)
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|
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': 'test@example.com',
|
|
'password': 'testpass123',
|
|
'password_confirm': 'testpass123',
|
|
})
|
|
assert response.status_code == 302
|
|
|
|
# Step 2: Login
|
|
response = client.post(reverse('users:login'), {
|
|
'email': 'test@example.com',
|
|
'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='test@example.com').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.
|