src/ids/clientOrderIndex.test.ts

import { describe, expect, it } from 'vitest';
import { clientOrderIndexSeed, createClientOrderIndex } from './clientOrderIndex.js';

describe('createClientOrderIndex', () => {
  it('seeds from the clock and counts modulo 2e9', () => {
    const now = 1_757_000_000_000;
    expect(clientOrderIndexSeed(now)).toBe(757_000_000);
    const c = createClientOrderIndex({ now: () => now });
    expect(c.current()).toBe(757_000_000);
    expect(c.next()).toBe(757_000_001);
    expect(c.next()).toBe(757_000_002);
  });

  it('wraps at the modulus and accepts an explicit seed', () => {
    const c = createClientOrderIndex({ seed: 9, modulo: 10 });
    expect(c.next()).toBe(0);
    expect(c.next()).toBe(1);
    expect(() => createClientOrderIndex({ modulo: 1 })).toThrow(RangeError);
    expect(() => createClientOrderIndex({ seed: -1 })).toThrow(RangeError);
  });
});