Build test data with factories

How to do it

Write one factory per kind of record, or use a library such as factory_boy or Fishery. Prefer factories to large shared fixture files, which tests come to depend on in hidden ways.

Example

const makeOrder = (overrides = {}) => ({
  id: crypto.randomUUID(),
  status: 'paid',
  total: 1999,
  currency: 'EUR',
  ...overrides,
});

test('refunds are blocked on unpaid orders', () => {
  expect(canRefund(makeOrder({ status: 'pending' }))).toBe(false);
});

# Python with factory_boy
class OrderFactory(factory.Factory):
    class Meta:
        model = Order

    status = "paid"
    total = 1999
    currency = "EUR"

def test_refunds_are_blocked_on_unpaid_orders():
    assert not can_refund(OrderFactory(status="pending"))

How to check

Change a default in a factory. Only tests about that field change result.