What are Django fixtures and when should you avoid using them? Django फिक्स्चर्स क्या हैं और इनका उपयोग कब नहीं करना चाहिए?

Fixtures are serialized snapshots of database data (JSON, YAML, or XML) that can be loaded into the test database before a test runs, using fixtures = ['products.json'] on a TestCase or the loaddata management command, useful for seeding a known baseline dataset quickly.

Fixtures are best avoided for complex or evolving models: they're brittle to schema changes (a new required field breaks every fixture file silently), hard to read and review in a diff, and don't express test intent clearly. The more maintainable alternative is factory libraries like factory_boy, which build model instances in Python code with sensible defaults and only the fields relevant to each test explicitly overridden.

# Fixture-based (harder to maintain)
class ProductTest(TestCase):
    fixtures = ['products.json']

# factory_boy alternative (recommended for evolving models)
class ProductFactory(factory.django.DjangoModelFactory):
    class Meta:
        model = Product
    name = factory.Sequence(lambda n: f"Product {n}")
    price = 100