datemath.mjs

#! /usr/bin/env -S node --experimental-modules

/*
 ** Copyright (C) 2018-2019 Bloomberg LP. All rights reserved.
 ** This code is governed by the license found in the LICENSE file.
 */

import Demitasse from '@pipobscure/demitasse';
const { describe, it, report } = Demitasse;

import Pretty from '@pipobscure/demitasse-pretty';
const { reporter } = Pretty;

import { strict as assert } from 'assert';
const { equal } = assert;

import * as Temporal from '@js-temporal/polyfill';

describe('Date.since(simple, simple)', () => {
  build('Before Leap Day', '2020-01-03', '2020-02-15');
  build('Before Leap Day', '2020-01-28', '2020-02-15');
  build('Before Leap Day', '2020-01-31', '2020-02-15');
  build('Cross Leap Day', '2020-01-31', '2020-06-30');
  build('After Leap Day', '2020-03-31', '2020-06-30');
  build('After Leap Day', '2020-03-25', '2020-07-31');
});
describe('Date.since(normal, normal)', () => {
  build('Month<2 & Month<2', '2018-01-20', '2019-01-05');
  build('Month>2 & Month>2', '2018-03-20', '2019-03-05');
  build('Month>2 & Month>2', '2018-04-20', '2019-04-05');
  build('Month<2 & Month>2', '2018-01-20', '2019-04-05');
  build('Month>2 & Month<2', '2018-03-20', '2019-01-05');
  build('Month>2 & Month<2', '2018-04-20', '2019-01-05');
});
describe('Date.since(leap, leap)', () => {
  build('Month<2 & Month<2', '2016-01-20', '2020-01-05');
  build('Month>2 & Month>2', '2016-03-20', '2020-04-05');
  build('Month>2 & Month>2', '2016-03-20', '2020-03-05');
  build('Month<2 & Month>2', '2016-01-20', '2020-02-05');
  build('Month>2 & Month<2', '2016-03-20', '2020-01-05');
  build('Month>2 & Month<2', '2016-04-20', '2020-01-05');
});
describe('Date.since(leap, normal)', () => {
  build('Month<2 & Month<2', '2016-01-20', '2017-01-05');
  build('Month>2 & Month>2', '2016-03-20', '2017-04-05');
  build('Month>2 & Month>2', '2016-04-20', '2017-03-05');
  build('Month<2 & Month>2', '2016-01-20', '2017-04-05');
  build('Month>2 & Month<2', '2016-03-20', '2017-01-05');
  build('Month>2 & Month<2', '2016-04-20', '2017-01-05');
});
describe('Date.since(normal, leap)', () => {
  build('Month<2 & Month<2', '2019-01-20', '2020-01-05');
  build('Month>2 & Month>2', '2019-03-20', '2020-04-05');
  build('Month>2 & Month>2', '2019-04-20', '2020-03-05');
  build('Month<2 & Month>2', '2019-01-20', '2020-04-05');
  build('Month>2 & Month<2', '2019-03-20', '2020-01-05');
  build('Month>2 & Month<2', '2019-04-20', '2020-01-05');
});

function build(name, sone, stwo) {
  const calendars = ['iso8601', 'gregory'];
  describe(name, () => {
    const largestUnits = ['years', 'months', 'weeks', 'days'];
    for (const calendar of calendars) {
      const [one, two] = [
        Temporal.PlainDate.from(sone).withCalendar(calendar),
        Temporal.PlainDate.from(stwo).withCalendar(calendar)
      ].sort(Temporal.PlainDate.compare);
      buildSub(one, two, largestUnits);
      buildSub(one.with({ day: 25 }), two.with({ day: 5 }), largestUnits);
      buildSub(one.with({ day: 30 }), two.with({ day: 29 }), largestUnits);
      buildSub(one.with({ day: 30 }), two.with({ day: 5 }), largestUnits);
    }
  });
}
function buildSub(one, two, largestUnits) {
  largestUnits.forEach((largestUnit) => {
    describe(`< ${one} : ${two} (${largestUnit})>`, () => {
      const dif = two.since(one, { largestUnit });
      const overflow = 'reject';
      if (largestUnit === 'months' || largestUnit === 'years') {
        // For months and years, `until` and `since` won't agree because the
        // starting point is always `this` and month-aware arithmetic behavior
        // varies based on the starting point.
        it(`(${two}).subtract(${dif}) => ${one}`, () => assert(two.subtract(dif).equals(one)));
        it(`(${two}).add(-${dif}) => ${one}`, () => assert(two.add(dif.negated()).equals(one)));
        const difUntil = one.until(two, { largestUnit });
        it(`(${one}).subtract(-${difUntil}) => ${two}`, () => assert(one.subtract(difUntil.negated()).equals(two)));
        it(`(${one}).add(${difUntil}) => ${two}`, () => assert(one.add(difUntil).equals(two)));
      } else {
        it('until() and since() agree', () => equal(`${dif}`, `${one.until(two, { largestUnit })}`));
        it(`(${one}).add(${dif}) => ${two}`, () => assert(one.add(dif, { overflow }).equals(two)));
        it(`(${two}).subtract(${dif}) => ${one}`, () => assert(two.subtract(dif, { overflow }).equals(one)));
        it(`(${one}).subtract(-${dif}) => ${two}`, () => assert(one.subtract(dif.negated(), { overflow }).equals(two)));
        it(`(${two}).add(-${dif}) => ${one}`, () => assert(two.add(dif.negated(), { overflow }).equals(one)));
      }
    });
  });
}

import { normalize } from 'path';
if (normalize(import.meta.url.slice(8)) === normalize(process.argv[1])) {
  report(reporter).then((failed) => process.exit(failed ? 1 : 0));
}