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Testing Advanced Date Formatting Patterns in iamkun/dayjs

This test suite validates the advanced formatting capabilities of the Day.js library, comparing its output with Moment.js for consistency. It covers date formatting patterns, localization, and timezone handling through comprehensive unit tests.

Test Coverage Overview

The test suite provides extensive coverage of Day.js’s advanced formatting features including:

Quarter formatting (Q)
Timestamp formatting (X, x)
Day of month ordinal formatting (Do)
24-hour time formatting (k, kk)
Week and year formatting (wo, gggg, GGGG)
Timezone offset naming (z, zzz)

Implementation Analysis

The testing approach uses Jest framework with MockDate for consistent date handling. Tests compare Day.js output directly with Moment.js to ensure compatibility and correct formatting implementation. Multiple plugins are extended including utc, timezone, isoWeek, and advancedFormat.

Technical Details

Testing tools and configuration include:

Jest as the testing framework
MockDate for date mocking
Multiple Day.js plugins integration
Locale testing with zh-cn and nl
Timezone testing with America/New_York

Best Practices Demonstrated

The test suite demonstrates several testing best practices:

Consistent before/after test setup
Comprehensive edge case handling
Cross-library validation
Isolated format testing
Localization verification
Bracket escaping validation

iamkun/dayjs

test/plugin/advancedFormat.test.js

            
import MockDate from 'mockdate'
import moment from 'moment'
import dayjs from '../../src'
import advancedFormat from '../../src/plugin/advancedFormat'
import isoWeek from '../../src/plugin/isoWeek'
import weekOfYear from '../../src/plugin/weekOfYear'
import weekYear from '../../src/plugin/weekYear'
import timezone from '../../src/plugin/timezone'
import utc from '../../src/plugin/utc'
import '../../src/locale/zh-cn'
import '../../src/locale/nl'

dayjs.extend(utc)
dayjs.extend(timezone)
dayjs.extend(isoWeek)
dayjs.extend(weekYear)
dayjs.extend(weekOfYear)
dayjs.extend(advancedFormat)

beforeEach(() => {
  MockDate.set(new Date())
})

afterEach(() => {
  MockDate.reset()
})

it('Format of invalid date', () => {
  expect(dayjs(null).format('z').toLowerCase()).toEqual(moment(null).format('z').toLowerCase())
})

it('Format empty string', () => {
  expect(dayjs().format()).toBe(moment().format())
})

it('Format Quarter Q', () => {
  expect(dayjs().format('Q')).toBe(moment().format('Q'))
})

it('Format Timestamp X x', () => {
  expect(dayjs().format('X')).toBe(moment().format('X'))
  expect(dayjs().format('x')).toBe(moment().format('x'))
})

it('Format Day of Month Do 1 - 31', () => {
  expect(dayjs().format('Do')).toBe(moment().format('Do'))
  let d = '2018-05-02 00:00:00.000'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-01 00:00:00.000'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-03 00:00:00.000'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-04 00:00:00.000'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-08 00:00:00.000'
  expect(dayjs(d).locale('nl').format('Do')).toBe(moment(d).locale('nl').format('Do'))
  d = '2018-05-11'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-12'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-13'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
  d = '2018-05-19 00:00:00.000'
  expect(dayjs(d).locale('nl').format('Do')).toBe(moment(d).locale('nl').format('Do'))
  d = '2018-05-22'
  expect(dayjs(d).format('Do')).toBe(moment(d).format('Do'))
})

it('Format Hour k kk 24-hour 1 - 24', () => {
  expect(dayjs().format('k')).toBe(moment().format('k'))
  expect(dayjs().format('kk')).toBe(moment().format('kk'))
  let d = '2018-05-02 00:00:00.000'
  expect(dayjs(d).format('k')).toBe('24')
  expect(dayjs(d).format('k')).toBe(moment(d).format('k'))
  expect(dayjs(d).format('kk')).toBe('24')
  expect(dayjs(d).format('kk')).toBe(moment(d).format('kk'))
  d = '2018-05-02 01:00:00.000'
  expect(dayjs(d).format('k')).toBe('1')
  expect(dayjs(d).format('k')).toBe(moment(d).format('k'))
  expect(dayjs(d).format('kk')).toBe('01')
  expect(dayjs(d).format('kk')).toBe(moment(d).format('kk'))
  d = '2018-05-02 23:59:59.999'
  expect(dayjs(d).format('k')).toBe('23')
  expect(dayjs(d).format('k')).toBe(moment(d).format('k'))
  expect(dayjs(d).format('kk')).toBe('23')
  expect(dayjs(d).format('kk')).toBe(moment(d).format('kk'))
})

it('Format Week of Year wo', () => {
  const d = '2018-12-01'
  expect(dayjs(d).format('wo')).toBe(moment(d).format('wo'))
  expect(dayjs(d).locale('zh-cn').format('wo'))
    .toBe(moment(d).locale('zh-cn').format('wo'))
})

it('Format Week of Year wo', () => {
  const d = '2018-12-01'
  expect(dayjs(d).format('wo')).toBe(moment(d).format('wo'))
  expect(dayjs(d).locale('zh-cn').format('wo'))
    .toBe(moment(d).locale('zh-cn').format('wo'))
})

it('Format Week Year gggg', () => {
  const d = '2018-12-31'
  expect(dayjs(d).format('gggg')).toBe(moment(d).format('gggg'))
})

it('Format Iso Week Year GGGG', () => {
  const d = '2021-01-01'
  expect(dayjs(d).format('GGGG')).toBe(moment(d).format('GGGG'))
})

it('Format Iso Week of Year', () => {
  const d = '2021-01-01'
  expect(dayjs(d).format('W')).toBe(moment(d).format('W'))
  expect(dayjs(d).format('WW')).toBe(moment(d).format('WW'))
})

it('Format offsetName z zzz', () => {
  const dtz = dayjs.tz('2012-03-11 01:59:59', 'America/New_York')
  expect(dtz.format('z')).toBe('EST')
  expect(dtz.format('zzz')).toBe('Eastern Standard Time')
  expect(dayjs().format('z')).toBeDefined()
  expect(dayjs().format('zzz')).toBeDefined()
})

it('Skips format strings inside brackets', () => {
  expect(dayjs().format('[Q]')).toBe('Q')
  expect(dayjs().format('[Do]')).toBe('Do')
  expect(dayjs().format('[gggg]')).toBe('gggg')
  expect(dayjs().format('[GGGG]')).toBe('GGGG')
  expect(dayjs().format('[w]')).toBe('w')
  expect(dayjs().format('[ww]')).toBe('ww')
  expect(dayjs().format('[W]')).toBe('W')
  expect(dayjs().format('[WW]')).toBe('WW')
  expect(dayjs().format('[wo]')).toBe('wo')
  expect(dayjs().format('[k]')).toBe('k')
  expect(dayjs().format('[kk]')).toBe('kk')
  expect(dayjs().format('[X]')).toBe('X')
  expect(dayjs().format('[x]')).toBe('x')
})