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/* eslint-env mocha */
import assert from 'power-assert'
import differenceInYears from '.'
describe('differenceInYears', function () {
it('returns the number of full years between the given dates', function () {
const result = differenceInYears(
new Date(2012, 6 /* Jul */, 2, 18, 0),
new Date(2011, 6 /* Jul */, 2, 6, 0)
)
assert(result === 1)
})
it('returns a negative number if the time value of the first date is smaller', function () {
const result = differenceInYears(
new Date(2011, 6 /* Jul */, 2, 6, 0),
new Date(2012, 6 /* Jul */, 2, 18, 0)
)
assert(result === -1)
})
it('accepts timestamps', function () {
const result = differenceInYears(
new Date(2014, 6 /* Jul */, 2).getTime(),
new Date(2010, 6 /* Jul */, 2).getTime()
)
assert(result === 4)
})
describe('leap days', function () {
it('supports past dates with right side after leap day', () => {
const result = differenceInYears(
new Date(2004, 1 /* Feb */, 29, 0, 0),
new Date(2002, 2 /* Mar */, 1, 0, 0)
)
assert(result === 1)
})
it('supports past dates with right side before leap day', () => {
const result = differenceInYears(
new Date(2004, 1 /* Feb */, 29, 0, 0),
new Date(2002, 1 /* Feb */, 28, 0, 0)
)
assert(result === 2)
})
it('supports future dates', () => {
const result = differenceInYears(
new Date(2004, 1 /* Feb */, 29, 0, 0),
new Date(2006, 2 /* Mar */, 1, 0, 0)
)
assert(result === -2)
})
it('supports equal dates of same year', () => {
const result = differenceInYears(
new Date(2004, 1 /* Feb */, 29, 0, 0),
new Date(2004, 1 /* Feb */, 29, 0, 0)
)
assert(result === 0)
})
it('supports equal dates of different years', () => {
const result = differenceInYears(
new Date(2008, 1 /* Feb */, 29, 0, 0),
new Date(2004, 1 /* Feb */, 29, 0, 0)
)
assert(result === 4)
})
})
describe('edge cases', function () {
it('the difference is less than a year, but the given dates are in different calendar years', function () {
const result = differenceInYears(
new Date(2015, 0 /* Jan */, 1),
new Date(2014, 11 /* Dec */, 31)
)
assert(result === 0)
})
it('the same for the swapped dates', function () {
const result = differenceInYears(
new Date(2014, 11 /* Dec */, 31),
new Date(2015, 0 /* Jan */, 1)
)
assert(result === 0)
})
it('the days and months of the given dates are the same', function () {
const result = differenceInYears(
new Date(2014, 8 /* Sep */, 5),
new Date(2012, 8 /* Sep */, 5)
)
assert(result === 2)
})
it('the given dates are the same', function () {
const result = differenceInYears(
new Date(2014, 8 /* Sep */, 5, 0, 0),
new Date(2014, 8 /* Sep */, 5, 0, 0)
)
assert(result === 0)
})
it('does not return -0 when the given dates are the same', () => {
function isNegativeZero(x: number): boolean {
return x === 0 && 1 / x < 0
}
const result = differenceInYears(
new Date(2014, 8 /* Sep */, 5, 0, 0),
new Date(2014, 8 /* Sep */, 5, 0, 0)
)
const resultIsNegative = isNegativeZero(result)
assert(resultIsNegative === false)
})
})
it('returns NaN if the first date is `Invalid Date`', function () {
const result = differenceInYears(
new Date(NaN),
new Date(2017, 0 /* Jan */, 1)
)
assert(isNaN(result))
})
it('returns NaN if the second date is `Invalid Date`', function () {
const result = differenceInYears(
new Date(2017, 0 /* Jan */, 1),
new Date(NaN)
)
assert(isNaN(result))
})
it('returns NaN if the both dates are `Invalid Date`', function () {
const result = differenceInYears(new Date(NaN), new Date(NaN))
assert(isNaN(result))
})
it('throws TypeError exception if passed less than 2 arguments', function () {
assert.throws(differenceInYears.bind(null), TypeError)
assert.throws(differenceInYears.bind(null, 1), TypeError)
})
})
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