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Testing Leap Year Detection Implementation in dayjs

This test suite validates the isLeapYear plugin functionality in dayjs, ensuring accurate leap year determination for date calculations. The tests verify both positive and negative cases using mock dates to maintain consistent testing conditions.

Test Coverage Overview

The test coverage focuses on validating the isLeapYear plugin’s core functionality.

Key areas tested include:

Verification of known leap years (2000)
Validation of non-leap years (2100)
Edge case testing for century years

The suite integrates with the dayjs core library and MockDate for consistent date handling.

Implementation Analysis

The testing approach utilizes Jest’s testing framework with MockDate for date manipulation control.

Key implementation patterns include:

Plugin extension pattern using dayjs.extend()
Before/after hooks for test environment setup
Direct assertion testing using expect().toBe()

Technical Details

Testing infrastructure includes:

Jest as the primary testing framework
MockDate for date manipulation
dayjs core library integration
isLeapYear plugin implementation

Configuration includes test setup and teardown via beforeEach and afterEach hooks.

Best Practices Demonstrated

The test suite demonstrates several testing best practices.

Notable practices include:

Proper test isolation using mock date reset
Clear test case organization
Efficient setup and teardown procedures
Focused test scope with specific assertions

iamkun/dayjs

test/plugin/isLeapYear.test.js

            
import MockDate from 'mockdate'
import dayjs from '../../src'
import isLeapYear from '../../src/plugin/isLeapYear'

dayjs.extend(isLeapYear)

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

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

it('IsLeapYear', () => {
  expect(dayjs('20000101').isLeapYear()).toBe(true)
  expect(dayjs('2100-01-01').isLeapYear()).toBe(false)
})