Menene jarrabawa taSnapshot?

Question

Accepted Answer

**Jarrabawa ta snapshot** tana kamawa da "snapshot" na wata fitowar (galibi fitowar da aka zana ta UI component ko tsarin bayani) kuma tana kwatanta jiyoyi masu gida a gida — kuma tana nuna lokacin da fitowar ta canja. Yana da amfani don gano canje da ba a niyya ba, amma yana da iyakancewa da ya kamata a fahimta.

## Yadda jarrabawa ta snapshot ke aiki

```text
1. First run → the test RECORDS the output (e.g. a rendered component) as a SNAPSHOT file
2. Later runs → COMPARE the current output to the saved snapshot:
   → MATCHES → pass; DIFFERS → fail (the output changed)
3. If the change is INTENTIONAL → UPDATE the snapshot (review the diff, then accept)
```

```js
// Jest snapshot test (e.g. a React component)
test('renders correctly', () => {
  const tree = render(<Button label="Click" />).toJSON();
  expect(tree).toMatchSnapshot();    // compares to the stored snapshot
});
```

## Amfani da fa'idodi

```text
✓ Detect UNINTENDED CHANGES — flags when output changes unexpectedly (UI, serialized data)
✓ FAST to write — no manual assertions for complex output; auto-captures the expected result
✓ Good for UI components (catch unexpected rendering changes), config, large data structures
```

## Iyakancewa (yi amfani da hankali)

```text
⚠️ Snapshots don't verify CORRECTNESS — they capture whatever output exists (even if WRONG);
   they only detect CHANGE, not that the output is RIGHT
⚠️ BLINDLY UPDATING snapshots (jest -u without reviewing) → defeats the purpose (accepting
   broken output) — a common bad habit
⚠️ Large/brittle snapshots → change often, get rubber-stamped, low value
→ Use for change detection; keep snapshots small/focused; REVIEW snapshot diffs;
  don't rely on them alone (combine with real assertions for behavior).
```

## Dalilin da ya sa ya matuhi

Fahimtawa ta jarrabawa ta snapshot yana da daraja saboda ita ce **dabarar da aka yi amfani da ita sosai** (musamman don UI) wacce yana aiki da kyau lokacin da aka yi mata amfani da kyau amma yana da matsala lokacin da aka yi mata amfani da ba daidai ba, don haka fahimta duka iyaka da iyakancewa nata yana da mahimmanci na aiki.

Jarrabawa ta snapshot — kamawa da fitowar (galibi UI component da aka zana ko tsarin bayani) kuma kwatanta jiyoyi masu gida a gida tare da snapshot da aka adana — yana **da amfani don gano canje da ba a niyya ba**: tana nuna lokacin da fitowar ta canja ba tilo ba (kula da canje da ba a niyya ba na zane UI ko canje ta tsarin bayani), yana **sauri wajen rubutu** (ji daɗi kai tsaye jiyoyi da aka bugi ba tare da yin karatun kuskure na kowane bayanin haɗi da zaita), kuma yana dace da UI components, setup, kuma tsarin bayani mai yawa.

Fahimtawa da fa'idodin nan yana bayyana yanda ake bugatawa, musamman a jarrabawa ta UI.

Ko da haka, fahimtawa ta **iyakancewa yana da mahimmanci sosai** don yi da kyau: snapshots **ba sa tabbatar da daidaitawa** — suna kamawa da fitowar da ta wanzu (ko da kuma ita ba daidai ba ne), kawai suna gano *canja* ba *daidaitawa* ba — sabili da haka snapshot na iya kulla bugawa fitowar da ba daidai ba.

**Babbai matsala shine buguwar snapshots ba kuskure ba** (guddu da umakinta ba tare da bincike ta bambanci ba), wanda ya karya dalili ta karbi bugawan jiyoyi da alama mai muni — dabigar da ba kyau ba.

Snapshots masu girma, da rashin ƙarfi waɗanda ke canja sau-sau sukan karba kuma suna ba da ƙaƙƙarfan amfani.

Fahimtawa ta amfani na daidai — don gano canja, kiyaye snapshots ƙaƙƙarfan kuma miƙa, **bincike snapshot bambanci** da hankali, kuma ba yi dogara kan su kawai ba (haɗa da ƙiyaye aiki na gaskiya) — yana nuna hoto mai karfi wacce ta baci buguwar da ba daidai ba.

Tun jiya jarrabawa ta snapshot ana yi amfani da ita sosai (musamman don UI) kuma yana da amfani don gano canja amma ana iya yi mata amfani da ba daidai ba (kulla bugawa, buguwar babu daidai), kuma tun jahimtawa duka iyaka kuma iyakancewa na ita yana baje da yayi amfani da kyau, kuma tun fahimta ta jarrabawa ta snapshot yana da daraja, nauyi-na-aiki na ilimi — dabarar da aka sha'awa a fahimta daidai, inda kulawar iyakancewa nata (gano canja, ba daidaitawa ba) kuma amfani na daidai (bincike bambanci, ba buguwar babu daidai ba) yana da mahimmanci kamar dabarar kanta, wanda ke nuna hoto maikarfi na jarrabawa.