import { describe, it, expect } from 'vitest'
import { DOW, DOW_EN, bydayFromDate } from '../src/lib/weekday.js'

describe('weekday', () => {
  it('DOW 有 7 项, 首项为周日', () => {
    expect(DOW).toHaveLength(7)
    expect(DOW[0]).toBe('周日')
    expect(DOW[6]).toBe('周六')
  })

  it('DOW_EN 按 JS getDay 索引 (0=周日)', () => {
    expect(DOW_EN).toEqual(['SU', 'MO', 'TU', 'WE', 'TH', 'FR', 'SA'])
  })

  it('bydayFromDate 返回 Date 对应的 BYDAY 编码', () => {
    // 2026-07-27 是周一 -> getDay()=1 -> 'MO'
    expect(bydayFromDate(new Date(2026, 6, 27))).toBe('MO')
    // 2026-08-01 是周六 -> getDay()=6 -> 'SA'
    expect(bydayFromDate(new Date(2026, 7, 1))).toBe('SA')
  })
})