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Validating Swedish Locale Date Formatting in dayjs

This test suite validates the Swedish (sv) locale implementation in the Day.js library, specifically focusing on ordinal date formatting. It ensures proper handling of Swedish date formats and ordinal indicators while preventing common formatting conflicts.

Test Coverage Overview

The test coverage focuses on Swedish locale-specific date formatting, particularly the ordinal indicator ‘a’ implementation. Key test scenarios include:

Validation of weekday names in Swedish
Proper formatting of ordinal numbers (1a, 2a)
Month name localization
Edge case testing for ordinal/meridiem conflicts

Implementation Analysis

The testing approach utilizes Jest’s testing framework with MockDate for consistent date handling. The implementation employs dayjs’s locale and plugin system, specifically incorporating the advancedFormat plugin for extended formatting capabilities.

Test patterns include isolated locale testing, format string composition, and explicit assertion of formatted output strings.

Technical Details

Testing infrastructure includes:

Jest as the primary testing framework
MockDate for date manipulation
Day.js core library
Advanced Format plugin integration
Swedish locale module

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Proper test isolation using beforeEach/afterEach hooks
Clear test case descriptions
Specific assertions for format verification
Modular plugin and locale loading
Consistent date mocking strategy

iamkun/dayjs

test/locale/sv.test.js

            
import MockDate from 'mockdate'
import dayjs from '../../src'
import advancedFormat from '../../src/plugin/advancedFormat'
import '../../src/locale/sv'

dayjs.extend(advancedFormat)

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

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

it('Swedish locale Do 1a not format to 1am', () => {
  expect(dayjs('2019-01-01').locale('sv').format('dddd Do MMMM'))
    .toBe('tisdag 1a januari')
  expect(dayjs('2019-01-02').locale('sv').format('dddd Do MMMM'))
    .toBe('onsdag 2a januari')
})