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Validating Croatian Locale Date Formatting in dayjs

This test suite validates the Croatian (hr) locale functionality in the Day.js library by comparing its date formatting output with Moment.js. The tests specifically focus on month formatting patterns and locale-specific date representations.

Test Coverage Overview

The test coverage focuses on validating Croatian locale date formatting across multiple format patterns.

Key areas tested include:

Full month name formatting (MMMM)
Abbreviated month formatting (MMM)
Combined date formats with day and year
Weekday name formatting

The suite tests 8 consecutive days to ensure consistency across date transitions.

Implementation Analysis

The testing approach employs parallel comparison between Day.js and Moment.js implementations.

Technical implementation features:

Iterative testing using for loop
Multiple format string patterns
Direct output comparison using Jest’s expect().toEqual()
Locale initialization and switching

Technical Details

Testing infrastructure includes:

Jest as the testing framework
Day.js with Croatian locale import
Moment.js as reference implementation
Format string patterns: ‘DD MMMM YYYY MMM’, ‘dddd, MMMM D YYYY’, ‘MMMM’, ‘MMM’

Best Practices Demonstrated

The test suite exemplifies several testing best practices for locale validation.

Notable practices include:

Comprehensive format pattern coverage
Reference implementation comparison
Multiple date sample testing
Isolated locale testing
Consistent format string constants

iamkun/dayjs

test/locale/hr.test.js

            
import moment from 'moment'
import dayjs from '../../src'
import '../../src/locale/hr'

it('Format month with locale function', () => {
  for (let i = 0; i <= 7; i += 1) {
    const dayjsUK = dayjs().locale('hr').add(i, 'day')
    const momentUK = moment().locale('hr').add(i, 'day')
    const testFormat1 = 'DD MMMM YYYY MMM'
    const testFormat2 = 'dddd, MMMM D YYYY'
    const testFormat3 = 'MMMM'
    const testFormat4 = 'MMM'
    expect(dayjsUK.format(testFormat1)).toEqual(momentUK.format(testFormat1))
    expect(dayjsUK.format(testFormat2)).toEqual(momentUK.format(testFormat2))
    expect(dayjsUK.format(testFormat3)).toEqual(momentUK.format(testFormat3))
    expect(dayjsUK.format(testFormat4)).toEqual(momentUK.format(testFormat4))
  }
})