Kepiye carane nggunakake asisten AI kanggo nulis unit test kanggo fungsi sing wis ana?

Question

Accepted Answer

Yen digunakake kanthi becik, AI iku apik banget ing bagean **enumerasi** saka testing — dheweke brainstorm edge case lan nulis boilerplate kanthi cepet. Nanging sampeyan kudu **verify manawa asertsi iku bermakna**, amarga AI bakal seneng nulis test sing lulus tanpa mbuktikake apa-apa.

## Workflow-e

1. **Wenehi dheweke fungsi plus kontrakne** — apa sing kudu ditindakake, tipe input/output, lan kepiye mengko nangani input sing ora valid. Test ora bisa luwih apik tinimbang spek sing sampeyan jelasake.
2. **Takon kanthi eksplisit kanggo edge case** — batas (0, kosong, maksimal), lan jalur kesalahan (null, negatif, tipe sing salah), ora mung happy path.
3. **Verify manawa asertsi iku bermakna** — test sing asert perilaku kode saiki (sanajan rusak) ora ana gunane. Cek saben asertsi encode kontrak sing *dimaksud*.

## Conto

```js
// Function under test, with its contract:
// applyDiscount(price, percent) -> price reduced by percent.
// Contract: percent must be 0..100; throws RangeError otherwise. price >= 0.
function applyDiscount(price, percent) {
  if (percent < 0 || percent > 100) throw new RangeError('percent out of range');
  return price - (price * percent) / 100;
}
```

```js
// AI-suggested test cases (Jest) — note the edge and error paths, not just happy path:
test('applies a normal discount', () => {
  expect(applyDiscount(100, 20)).toBe(80);       // happy path
});
test('0% leaves price unchanged', () => {
  expect(applyDiscount(100, 0)).toBe(100);       // boundary: lower edge
});
test('100% makes it free', () => {
  expect(applyDiscount(100, 100)).toBe(0);       // boundary: upper edge
});
test('rejects percent above 100', () => {
  expect(() => applyDiscount(100, 150)).toThrow(RangeError); // error path
});
```

AI ngusulake kasus batas (0 lan 100) lan jalur kesalahan sing bisa aja lali sampeyan. Tugas sampeyan yaiku konfirmasi `toBe(80)` iku nilai sing *bener* dikarepake, ora mung apa sing kebetulan dibaliki fungsi.

## Kok penting

Bagean sing angel saka testing dudu ngetik `test(...)` blok — iku **mikir kasus sing yen ora mangkono bakal ono yang terlewat**, lan AI iku bener apik ing jangkauan kuwi. Nanging dheweke ora ngerti apa kode sampeyan *kudu* ditindakake menawa sampeyan ora ngomong, dadi yen ora dikontrol dheweke cenderung nulis **test sing ngganteni implementasi** (lulus, nanging bakal lulus sanajan fungsi iku salah). Nganggep AI minangka generator edge-case nalika sampeyan duwe asertsi ngasili cakupan luas lan karektipan nyata — kecepatan saka AI, pertimbangan saka sampeyan.