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Copy pathuseLocalStorage.test.ts
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86 lines (64 loc) · 2.25 KB
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import { renderHook, act, waitFor } from '@testing-library/react';
import { describe, it, expect, beforeEach, vi } from 'vitest';
import { useLocalStorage } from './useLocalStorage';
describe('useLocalStorage', () => {
beforeEach(() => {
localStorage.clear();
vi.restoreAllMocks();
});
it('returns the initial value when storage is empty', () => {
const { result } = renderHook(() => useLocalStorage('username', ''));
expect(result.current[0]).toBe('');
});
it('loads an existing value from localStorage', async () => {
localStorage.setItem('username', JSON.stringify('ganesh'));
const { result } = renderHook(() => useLocalStorage('username', ''));
await waitFor(() => {
expect(result.current[0]).toBe('ganesh');
});
});
it('writes updates to localStorage', () => {
const setItemSpy = vi.spyOn(Storage.prototype, 'setItem');
const { result } = renderHook(() => useLocalStorage('username', ''));
act(() => {
result.current[1]('ganesh');
});
expect(result.current[0]).toBe('ganesh');
expect(setItemSpy).toHaveBeenCalledWith('username', JSON.stringify('ganesh'));
});
it('falls back to initial value when getItem throws', () => {
vi.spyOn(window.localStorage, 'getItem').mockImplementation(() => {
throw new Error('Storage unavailable');
});
const { result } = renderHook(() => useLocalStorage('username', 'fallback'));
expect(result.current[0]).toBe('fallback');
});
it('does not crash when setItem throws', () => {
vi.spyOn(window.localStorage, 'setItem').mockImplementation(() => {
throw new Error('Quota exceeded');
});
const { result } = renderHook(() => useLocalStorage('username', ''));
expect(() => {
act(() => {
result.current[1]('ganesh');
});
}).not.toThrow();
expect(result.current[0]).toBe('ganesh');
});
it('supports generic object values', async () => {
const user = {
name: 'Ganesh',
score: 100,
};
localStorage.setItem('user', JSON.stringify(user));
const { result } = renderHook(() =>
useLocalStorage<typeof user>('user', {
name: '',
score: 0,
})
);
await waitFor(() => {
expect(result.current[0]).toEqual(user);
});
});
});