Apa iku test fixtures lan setup/teardown?

Question

Accepted Answer

**Test fixtures** yaiku setup tetap (data, object, state) sing dibutuhake tes kanggo mlaku, lan **setup/teardown** methods nyedhiyakake lan mbersihake konteks iki sadurunge lan sawise tes. Dheweke nyuda duplikasi lan mesthekake tes mlaku ing state konsisten lan terisolasi.

## Setup lan teardown

```text
SETUP → runs BEFORE tests to prepare the context (create objects, data, connections)
TEARDOWN → runs AFTER tests to CLEAN UP (close connections, delete data, reset state)
→ frameworks provide hooks:
  beforeEach / afterEach → before/after EACH test (fresh state per test — common)
  beforeAll / afterAll → once before/after ALL tests in a group (shared expensive setup)
```

```js
describe('UserService', () => {
  let service, db;
  beforeEach(() => {                 // fresh setup for EACH test (isolation)
    db = createTestDb();
    service = new UserService(db);
  });
  afterEach(() => db.close());        // clean up after each test

test('creates a user', () => { /* uses the fresh service/db */ });
});
```

## Fixtures — data/state tes sing bisa dienggo maneh

```text
FIXTURES → predefined data/objects tests use (a known starting state):
  → e.g. a sample user, a set of records, a configured object
  → FACTORIES → generate test data flexibly (build objects with sensible defaults +
    overrides) — better than hardcoded data for varied scenarios
→ reduce duplication; give tests consistent, known data to work with
```

## Praktik sing paling apik

```text
✓ Prefer beforeEach (fresh state per test) → ISOLATION (tests don't affect each other)
✓ Clean up in teardown → no leftover state causing flaky/order-dependent tests
✓ Keep setup minimal and clear; use factories for flexible test data
✓ Don't share MUTABLE state across tests (a cause of flakiness/order-dependence)
```

## Apa gunane

Ngerteni test fixtures lan setup/teardown iku penting amarga dheweke **penting banget kanggo nulis tes sing resik, terisolasi, lan mudah dirawat**, mula dadi ilmu praktis sing migunani.

Tes butuh konteks awal sing konsisten (data, object, state), lan **setup/teardown** methods (`beforeEach`/`afterEach` lan `beforeAll`/`afterAll` hooks sing diwadhaké framework) nyedhiyakake konteks iki sadurunge tes lan mbersihake sawise — nyuda duplikasi (setup sing dienggo bareng ditulis sapisan tinimbang ing saben tes) lan mesthekake tes mlaku ing state sing dipesthekake.

Ngerteni hooks iki lan kapan nganggo saben-saben (beforeEach kanggo state seger saben tes, beforeAll kanggo setup bareng sing larang) kudu banget kanggo ngatur-atur tes kanthi apik.

Ngerteni **fixtures** (data lan object tes sing wis ditentokake, menehi tes state awal sing dipesthekake) lan **factories** (ngasilake data tes kanthi luwes pakai default lan override sing wajar, luwih apik tinimbang data hard-coded kanggo skenario macem-macem) iku penting banget kanggo nyawisake tes data konsisten lan mudah dikontrol.

Paling penting, ngerteni **praktik sing paling apik** nyambung marang mutu tes: luwih seneng `beforeEach` kanggo **state seger saben tes** mesthekake **isolasi** (tes ora pengaruhi siji liyane — kudu banget kanggo tes sing setia), **mbersihake ing teardown** nyegah state sisa sing nyebabake tes flaky lan gumantung-gumantunga (asal umum flakiness), lan **ora magi mutable state medhhar tes** nyegah gumantung-gumantunga lan flakiness.

Praktik-praktik iki langsung ndhukung isolasi tes lan determinisme sing tes apik butuhake.

Amarga tes butuh setup lan cleanup konsisten, lan amarga fixtures lan setup/teardown (dienggo kanthi bener, pakai isolasi lan cleanup sing tepat) nyuda duplikasi lan mesthekake state terisolasi lan deterministic sing tes setia gumantung, ngerteni test fixtures lan setup/teardown iku ilmu sing penting lan relevan praktis — penting kanggo nulis tes resik, terisolasi, lan mudah dirawat, langsung ndhukung isolasi lan determinisme sing bedo-bedo tes setia lan tes flaky, katrampilan migunani diterapake ing ngatur-atur meh saben test suite.