Test files exist for critical application paths

AI-built projects that ship without tests accumulate risk with every change. There is no safety net when modifying working code — a refactor that breaks authentication or payment processing goes undetected until a user reports it. ISO 25010 maintainability.testability directly measures this gap. SSDF PW.8 requires testing as a software assurance control. The absence of tests is especially costly in AI-assisted development where the model makes structural changes across sessions that can silently break previously working behavior.

Start with the highest-value tests: critical business logic and API route behavior. Set up a test runner:

npm install -D vitest @vitest/coverage-v8
# or: npm install -D jest @types/jest ts-jest

Write your first test covering the most critical logic path:

// tests/lib/scoring.test.ts
import { computeCategoryScore } from '../lib/scoring'

describe('computeCategoryScore', () => {
  it('returns null when all checks are skipped', () => {
    const checks = [{ result: 'skip' }, { result: 'skip' }]
    expect(computeCategoryScore(checks)).toBeNull()
  })
})

Five targeted tests covering auth, payments, and core logic are more valuable than fifty snapshot tests of static UI components.