Integration testing ni nini?

Question

Accepted Answer

**Integration testing** inathibitisha kwamba **vijenzi vingi au vitengo vya nchi vinaishi kwa usahihi pamoja** — inajaribu mwingiliano na nukta za ujumuishaji (kama nambari na hifadhi ya data, huduma zinazohitaji kila nyingine, au moduli zilizounganishwa). Inakamata matatizo ambayo mtihani wa vitengo (ambayo huweka vitengo kando) haukosi.

## Kile integration testing kinathibitisha

```text
Integration tests verify COMPONENTS WORKING TOGETHER (not in isolation):
  → code + DATABASE (does the data layer actually work with a real DB?)
  → service A calling service B / an external API
  → multiple modules/units combined; the integration POINTS between them
→ catches issues in how parts INTERACT — which unit tests (isolated) can't catch.
```

## Kwa nini mitihani ya ujumuishaji ina umuhimu (vs mtihani wa vitengo)

```text
UNIT tests isolate units (mocking dependencies) → fast, but DON'T verify real integration:
  → a unit can pass its tests but FAIL when combined (wrong assumptions about a dependency,
    a real DB query that's wrong, an API contract mismatch, config issues)
INTEGRATION tests use REAL (or realistic) dependencies → catch these interaction bugs:
  → wiring/configuration errors, data layer issues, contract mismatches between components
→ Integration tests verify the parts actually work TOGETHER.
```

## Mfano na mawazo

```js
// integration test: the repository actually works with a (test) database
test('UserRepository saves and retrieves a user', async () => {
  const repo = new UserRepository(testDb);     // REAL test database
  await repo.save({ name: 'Ann' });
  const user = await repo.findByName('Ann');    // real query
  expect(user.name).toBe('Ann');
});
```

```text
→ SLOWER than unit tests (real I/O, setup); use a TEST database/environment
→ Test important integration points (data access, key service interactions, APIs)
→ Fewer than unit tests (the pyramid middle); manage test data/state carefully
```

## Kwa nini ina umuhimu

Kuelewa integration testing ni muhimu kwa sababu **kinakamata aina ya hitilafu ambazo mtihani wa vitengo hauwezi** — matatizo katika jinsi vijenzi vinavyofanya kazi pamoja — kwa hivyo ni ujumbe muhimu kwa mtihani wa kina.

Hali ya mtihani wa vitengo inathibitisha vitengo tofauti katika kujua kwa kuuza (kuiga utegemezi), kujua hii kumaanisha **haiwezi kuangalia ujumuishaji wa kweli**: kitengo kinaweza kupitia mtihani wake lakini kushindwa wakati na vijenzi vingine (kwa sababu ya dhana ndogo kuhusu utegemezi, hifadhi ya data halisi ambayo inauliza kuwa sio sahihi, API hitilafu ya mkataba, au matatizo ya usanidi). **Mitihani ya ujumuishaji** inajaza njia hii kwa kujaribu **vijenzi vinavyofanya kazi pamoja na utegemezi wa kweli (au ukaribu)** — kuangalia kwamba nambari halisi inafanya kazi na hifadhi ya data halisi, kwamba huduma zinazoingiliana kwa usahihi, na kwamba nukta za ujumuishaji zina kazi — kinakamata usambazaji, safu ya data, na matatizo ya hitilafu ya mkataba ambayo mtihani wa vitengo vya kujua haukosi.

Kuelewa mahusiano haya yanayosambaza (mtihani wa vitengo kwa nambari ya kujua, mitihani ya ujumuishaji kwa mwingiliano wa kweli) ni muhimu kwa mtihani wa kina, kwa sababu kamata siyo yenye kutosha.

Kuelewa **mawazo** — kwamba mitihani ya ujumuishaji ni polepole (I/O na kusanidi halisi, kwa hivyo inakaa katikati ya piramidi na wachache kuliko mtihani wa vitengo), tumia hifadhi za mtihani/mazingira, kuzama katika nukta muhimu za ujumuishaji (upatikanaji wa data, mwingiliano muhimu wa huduma, APIs), na kuhitaji simu ya mtihani wa hali/usimamizi — kuakisi ujumuishaji wa mtihani halisi.

Mitihani ya ujumuishaji hutoa ujumbe kwamba sehemu zilizokusanywa zina kazi, ambayo mtihani wa vitengo peke yake hauwezi.

Kwa sababu programu za kweli zina vijenzi vinavyoingiliana na hitilafu za ujumuishaji (matatizo ya hifadhi ya data, hitilafu za mkataba, hitilafu za usanidi) ni kawaida na haukosi na mtihani wa vitengo, na kwa sababu integration testing inakamata kuwanyonyesha kwa kuangalia vijenzi vina kazi pamoja, kuelewa integration testing ni ujumbe muhimu, ujumuishaji wa halisi — kumala kumala ya mtihani wa vitengo ambayo inakamata hitilafu ya mwingiliano, muhimu kwa mtihani wa kina ambao inathibitisha si vitengo vya kujua lakini kwamba sehemu za mfumo halisi zina kazi pamoja kwa usahihi.