Randomized IDs cause snapshot test failures in Jest, Vitest, and Playwright. The mocking module allows you to seed the internal Web Crypto generator with a deterministic Mulberry32 PRNG during tests.

Usage in Test Suites

js

import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import { seed, resetMocks, uuidv4, nanoId } from '@readytools/id';

describe('User Snapshot Testing', () => {
  beforeEach(() => {
    // Seed with a constant number for deterministic output
    seed(42);
  });

  afterEach(() => {
    // Always restore secure native Web Crypto
    resetMocks();
  });

  it('generates predictable IDs in snapshots', () => {
    const id1 = uuidv4();
    const id2 = nanoId();
    
    // Will always produce the exact same values on every run
    expect(id1).toBe('51336c53-b09b-449e-ba63-005fa95781a7');
  });
});

Important Security Notice

Warning: Testing Only

Never call seed() in production code. Seeding replaces cryptographically secure randomness with a 32-bit pseudo-random algorithm. Always invoke resetMocks() in test teardown hooks.