Every test file contains at least one assertion

An assertion-free test file is indistinguishable from a passing test in CI — it runs, it exits 0, and it tells you nothing. AI-generated test suites routinely produce these: scaffolded describe/it blocks that call setup helpers but never verify a return value, a side effect, or a thrown error. The gap only surfaces when a real defect slips to production and you realize your test suite was never checking anything. ISO-25010:2011 testability requires that tests can actually detect faults; assertion-free files by definition cannot.

Add at least one assertion to every it/test block. Every call to createUser, fetchOrder, or any production function should be followed by an expect on its return value or side effect. Replace empty or setup-only test bodies with real verifications:

// Before: passes when createUser is completely broken
it('creates a user', async () => {
  await createUser({ email: 'test@example.com' })
})

// After: fails if id, email, or timestamp is wrong
it('creates a user', async () => {
  const user = await createUser({ email: 'test@example.com' })
  expect(user.id).toBeDefined()
  expect(user.email).toBe('test@example.com')
  expect(user.createdAt).toBeInstanceOf(Date)
})