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78 lines (57 loc) · 2.4 KB
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import { renderHook, act } from '@testing-library/react';
import { describe, it, expect, beforeEach, vi } from 'vitest';
import { useLocalStorage } from './useLocalStorage';
describe('useLocalStorage - Empty & Fallback Edge Cases', () => {
beforeEach(() => {
localStorage.clear();
vi.restoreAllMocks();
});
it('handles empty array as initial value', () => {
const { result } = renderHook(() => useLocalStorage<string[]>('list', []));
expect(result.current[0]).toEqual([]);
act(() => {
result.current[1](['item1']);
});
expect(result.current[0]).toEqual(['item1']);
expect(JSON.parse(localStorage.getItem('list') || '[]')).toEqual(['item1']);
});
it('handles null as initial value', () => {
const { result } = renderHook(() => useLocalStorage<string | null>('user', null));
expect(result.current[0]).toBeNull();
act(() => {
result.current[1]('ganesh');
});
expect(result.current[0]).toBe('ganesh');
expect(JSON.parse(localStorage.getItem('user') || 'null')).toBe('ganesh');
});
it('handles empty object as initial value', () => {
const { result } = renderHook(() => useLocalStorage<Record<string, unknown>>('config', {}));
expect(result.current[0]).toEqual({});
act(() => {
result.current[1]({ theme: 'dark' });
});
expect(result.current[0]).toEqual({ theme: 'dark' });
expect(JSON.parse(localStorage.getItem('config') || '{}')).toEqual({ theme: 'dark' });
});
it('falls back when localStorage key does not exist', () => {
const { result } = renderHook(() => useLocalStorage('missing-key', 'default'));
expect(result.current[0]).toBe('default');
});
it('gracefully falls back from corrupted JSON and recovers after update', () => {
const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
const key = 'corrupted';
const initial = { a: 1 };
localStorage.setItem(key, 'invalid-json-{');
const { result } = renderHook(() => useLocalStorage(key, initial));
// Fallback to initial value
expect(result.current[0]).toEqual(initial);
// Verify recovery: setting a new value should overwrite corrupted data
act(() => {
result.current[1]({ a: 2 });
});
expect(result.current[0]).toEqual({ a: 2 });
expect(JSON.parse(localStorage.getItem(key)!)).toEqual({ a: 2 });
expect(errorSpy).not.toHaveBeenCalled();
errorSpy.mockRestore();
});
});