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Testing Icelandic Locale Implementation in dayjs

This test suite validates the Icelandic (is) locale implementation in Day.js, specifically focusing on relative time formatting. It ensures compatibility with Moment.js and verifies correct translations for various time intervals and suffixes.

Test Coverage Overview

The test suite provides comprehensive coverage of relative time formatting in Icelandic:

Tests various time units (seconds to years)
Validates singular and plural forms
Covers past and future expressions
Tests with and without time suffixes

Implementation Analysis

The testing approach employs Jest’s describe/it blocks to organize test cases logically. MockDate is used to ensure consistent date handling across tests. The implementation validates both Day.js output against predefined expectations and ensures compatibility with Moment.js formatting.

Technical Details

Testing tools and configuration:

Jest as the testing framework
MockDate for date manipulation
Day.js with relative time plugin
Moment.js for compatibility testing
Structured test data using expectations array

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Consistent test structure and organization
Comprehensive edge case coverage
Clear separation of test scenarios
Efficient test data management using arrays
Proper setup and teardown with beforeEach/afterEach

iamkun/dayjs

test/locale/is.test.js

            
import MockDate from 'mockdate'
import moment from 'moment'
import dayjs from '../../src'
import '../../src/locale/is'
import relativeTime from '../../src/plugin/relativeTime'

dayjs.extend(relativeTime)

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

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

const expectations = [
  [1, 's', 'nokkrar sekúndur', 'fyrir nokkrum sekúndum síðan', 'eftir nokkrar sekúndur'],
  [1, 'm', 'mínúta', 'fyrir mínútu síðan', 'eftir mínútu'],
  [1, 'h', 'klukkustund', 'fyrir klukkustund síðan', 'eftir klukkustund'],
  [1, 'd', 'dagur', 'fyrir degi síðan', 'eftir dag'],
  [1, 'M', 'mánuður', 'fyrir mánuði síðan', 'eftir mánuð'],
  [1, 'y', 'ár', 'fyrir ári síðan', 'eftir ár'],
  [2, 'm', '2 mínútur', 'fyrir 2 mínútum síðan', 'eftir 2 mínútur'],
  [2, 'h', '2 klukkustundir', 'fyrir 2 klukkustundum síðan', 'eftir 2 klukkustundir'],
  [2, 'd', '2 dagar', 'fyrir 2 dögum síðan', 'eftir 2 daga'],
  [2, 'M', '2 mánuðir', 'fyrir 2 mánuðum síðan', 'eftir 2 mánuði'],
  [2, 'y', '2 ár', 'fyrir 2 árum síðan', 'eftir 2 ár'],
  [21, 'm', '21 mínúta', 'fyrir 21 mínútu síðan', 'eftir 21 mínútu'],
  [21, 'h', '21 klukkustund', 'fyrir 21 klukkustund síðan', 'eftir 21 klukkustund'],
  [21, 'd', '21 dagur', 'fyrir 21 degi síðan', 'eftir 21 dag'],
  [21, 'y', '21 ár', 'fyrir 21 ári síðan', 'eftir 21 ár']
]

describe('moment compatibility', () => {
  it('without suffix', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, expectationWithoutSuffix] = expectation

      const momentResult = moment()
        .add(offset, unit)
        .locale('is')
        .fromNow(true)

      expect(expectationWithoutSuffix).toBe(momentResult)
    })
  })

  it('past', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, , pastExpectation] = expectation

      const momentResult = moment()
        .add(-offset, unit)
        .locale('is')
        .fromNow()

      expect(pastExpectation).toBe(momentResult)
    })
  })

  it('future', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, , , futureExpectation] = expectation

      const momentResult = moment()
        .add(offset, unit)
        .locale('is')
        .fromNow()

      expect(futureExpectation).toBe(momentResult)
    })
  })
})

describe('Icelandic output matches moment output', () => {
  it('without suffix', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, expectationWithoutSuffix] = expectation

      const result = dayjs()
        .add(offset, unit)
        .locale('is')
        .fromNow(true)

      expect(result).toBe(expectationWithoutSuffix)
    })
  })

  it('past', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, , pastExpectation] = expectation

      const result = dayjs()
        .add(-offset, unit)
        .locale('is')
        .fromNow()

      expect(result).toBe(pastExpectation)
    })
  })

  it('future', () => {
    expectations.forEach((expectation) => {
      const [offset, unit, , , futureExpectation] = expectation

      const result = dayjs()
        .add(offset, unit)
        .locale('is')
        .fromNow()

      expect(result).toBe(futureExpectation)
    })
  })
})