Back to Repositories

Validating Date Manipulation Operations in Day.js Library

This test suite validates the date manipulation functionality in the Day.js library, comparing its behavior with Moment.js for consistency. The suite focuses on testing startOf/endOf operations and time addition/subtraction methods across different time units and locales.

Test Coverage Overview

The test coverage encompasses core date manipulation operations including:

StartOf/EndOf operations for various time units (year, month, day, week, hour, etc.)
Locale-specific week calculations for multiple languages
Time addition with different units and decimal values
Time subtraction operations

Implementation Analysis

The testing approach utilizes Jest’s describe/it blocks for organized test suites. MockDate is employed to ensure consistent date-based testing across executions. The implementation compares Day.js results against Moment.js as the reference implementation, using value-based equality checks.

Technical Details

Testing Framework: Jest
Mocking Utility: MockDate
Reference Library: Moment.js
Test Setup: beforeEach/afterEach hooks for date mocking
Assertion Style: Direct valueOf() comparisons

Best Practices Demonstrated

The test suite exhibits several testing best practices:

Consistent test environment setup and teardown
Comprehensive edge case testing with decimal values
Systematic verification across multiple locale settings
Parallel validation against an established library
Clear test case organization and naming

iamkun/dayjs

test/manipulate.test.js

            
import moment from 'moment'
import MockDate from 'mockdate'
import dayjs from '../src'
import '../src/locale/zh-cn'
import '../src/locale/ar'

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

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

describe('StartOf EndOf', () => {
  it('StartOf EndOf Year ... with s and upper case', () => {
    const testArr = ['Year', 'year', 'YearS', 'month', 'day', 'date',
      'week', 'hour', 'minute', 'second']
    testArr.forEach((d) => {
      expect(dayjs().startOf(d).valueOf()).toBe(moment().startOf(d).valueOf())
      expect(dayjs().endOf(d).valueOf()).toBe(moment().endOf(d).valueOf())
    })
  })

  it('StartOf EndOf Other -> no change', () => {
    expect(dayjs().startOf('otherString').valueOf()).toBe(moment().startOf('otherString').valueOf())
    expect(dayjs().endOf('otherString').valueOf()).toBe(moment().endOf('otherString').valueOf())
  })

  it('StartOf week with locale', () => {
    const testDate = [undefined, '2019-02-10', '2019-02-11', '2019-02-12', '2019-02-13', '2019-02-14', '2019-02-15', '2019-02-16']
    const testLocale = ['zh-cn', 'ar', 'en']
    testDate.forEach((d) => {
      testLocale.forEach((l) => {
        expect(dayjs(d).locale(l).startOf('week').date())
          .toBe(moment(d).locale(l).startOf('week').date())
        expect(dayjs(d).locale(l).endOf('week').date())
          .toBe(moment(d).locale(l).endOf('week').date())
      })
    })
  })
})


it('Add Time days', () => {
  expect(dayjs().add(1, 'ms').valueOf()).toBe(moment().add(1, 'ms').valueOf())
  expect(dayjs().add(1, 'milliseconds').valueOf()).toBe(moment().add(1, 'milliseconds').valueOf())
  expect(dayjs().add(1, 's').valueOf()).toBe(moment().add(1, 's').valueOf())
  expect(dayjs().add(1, 'seconds').valueOf()).toBe(moment().add(1, 'seconds').valueOf())
  expect(dayjs().add(1, 'm').valueOf()).toBe(moment().add(1, 'm').valueOf())
  expect(dayjs().add(1, 'minutes').valueOf()).toBe(moment().add(1, 'minutes').valueOf())
  expect(dayjs().add(1, 'h').valueOf()).toBe(moment().add(1, 'h').valueOf())
  expect(dayjs().add(1, 'hours').valueOf()).toBe(moment().add(1, 'hours').valueOf())
  expect(dayjs().add(1, 'w').valueOf()).toBe(moment().add(1, 'w').valueOf())
  expect(dayjs().add(1, 'weeks').valueOf()).toBe(moment().add(1, 'weeks').valueOf())
  expect(dayjs().add(1, 'd').valueOf()).toBe(moment().add(1, 'd').valueOf())
  expect(dayjs().add(1, 'days').valueOf()).toBe(moment().add(1, 'days').valueOf())
  expect(dayjs().add(1, 'M').valueOf()).toBe(moment().add(1, 'M').valueOf())
  expect(dayjs().add(1, 'y').valueOf()).toBe(moment().add(1, 'y').valueOf())
  expect(dayjs('20111031').add(1, 'months').valueOf()).toBe(moment('20111031').add(1, 'months').valueOf())
  expect(dayjs('20160131').add(1, 'months').valueOf()).toBe(moment('20160131').add(1, 'months').valueOf())
  expect(dayjs('20160229').add(1, 'year').valueOf()).toBe(moment('20160229').add(1, 'year').valueOf())

  expect(dayjs().add('2', 'years').valueOf()).toBe(moment().add('2', 'years').valueOf())
})

it('Add Time with decimal', () => {
  expect(dayjs().add(0.4, 'day').valueOf()).toBe(moment().add(0.4, 'day').valueOf())
  expect(dayjs().add(0.5, 'day').valueOf()).toBe(moment().add(0.5, 'day').valueOf())
  expect(dayjs().add(0.4, 'week').valueOf()).toBe(moment().add(0.4, 'week').valueOf())
  expect(dayjs().add(0.5, 'week').valueOf()).toBe(moment().add(0.5, 'week').valueOf())
})

it('Subtract Time days', () => {
  expect(dayjs().subtract(1, 'days').valueOf()).toBe(moment().subtract(1, 'days').valueOf())
})