Yadda kuke a gwaji da logician jiha?

Question

Accepted Answer

Gwajin logician jiha ya haifar da tabbacin cewa juyawanka jiha da sabuntawa sune daidai. Dabarun ya dogara ne akan *yadda* logician ke tsareki — ayyuka masu tsabta (reducers) sune mafi saukar a gwaji, don haka jiha mai kyau a hannu kuma jiha mai kyau a gwaji ne.

## Gwaji murjan ayyuka masu tsabta kai tsaye (halayen mafi saukar da mafi girma)

```js
// reducers are pure: (state, action) => newState → trivial to test, no mocks
describe("todosReducer", () => {
  it("adds a todo", () => {
    const initial = [];
    const next = todosReducer(initial, { type: "todos/added", payload: { id: 1, text: "A" } });
    expect(next).toEqual([{ id: 1, text: "A" }]);
    expect(initial).toEqual([]); // ✅ verify the original wasn't mutated (immutability)
  });
});
```

Domin reducers ayyuka masu tsabta ne, kun kira su ne kawai tare da abubuwan shiga kuma tabbatar da abubuwan fito — babu fitar, babu buga, sauri da tabbatacce. Wannan shine *why* tsarin murjan masu tsabta shine ita ce mai kima sosai.

## Gwaji zabbin

```js
it("selects the cart total", () => {
  const state = { cart: { items: [{ price: 10 }, { price: 5 }] } };
  expect(selectCartTotal(state)).toBe(15);
});
```

## Gwaji na hooks personalized / logician ma'ajiyar

```jsx
import { renderHook, act } from "@testing-library/react";

it("increments", () => {
  const { result } = renderHook(() => useCounter());
  act(() => result.current.increment()); // act wraps state updates
  expect(result.current.count).toBe(1);
});
```

`renderHook` + `act` ba ya ba da damar gwajin logician jiha na hook/ma'aji a kewaye.

## Gwaji abubuwan tare da hali, ba ta ciki ba

```jsx
import { render, screen, fireEvent } from "@testing-library/react";

it("shows the count after clicking", () => {
  render(<Counter />);
  fireEvent.click(screen.getByRole("button"));
  expect(screen.getByText("1")).toBeInTheDocument(); // assert the rendered RESULT
});
```

Gwaji abubuwan da mai amfani ya ga/yi (hali), ba bayanan aiwatarwa ba — don refactors ba su karya gwajin ba.

## Gwaji jiha da jiya (buga hanyar sadarwa)

```js
// mock fetch/API (e.g. MSW), then assert loading → success/error transitions
it("handles fetch error → error state", async () => { ... });
```

Yi amfani da MSW ko bugaje don gwajin loading/nasara/kuskure juyawa ta daidai.

## Abubuwan da za a ba da fifiko

```text
Reducers/selectors/pure logic → unit test thoroughly (cheap, high value)
Component behavior           → integration test key user flows
Async flows                  → test transitions with mocked APIs
Don't test framework internals or trivial setters
```

## Me yasa ya cancancanta

Kuskure na jiha yana cikin masu fa'ida da yawa, saboda haka gwajin logician jiha yana da ƙima.

A muhimmancinsa, **jiha mai kyau a hannu ita ce ta karɓa a ajiya**: murjan masu tsabta da zabbin isu ƙarɓa a gwaji a nauyinsa (babu bugaje, tabbatacce), wanda shine muhimmin argument don wannan gidanski.

Sanin cewa a gwaji reducers/zabbin kai tsaye, hooks tare da `renderHook`, abubuwan tare da hali da mai amfani ya ga, da abubuwan da jiya tare da hanyoyi da bugajje — yayin da jinda bugajen gida masu nazari — yana ba da gargajiye fitar da logician da mafi yiwuwar kawo da ƙwararrun bugu.