Date Kata SoCraCan

date-kata.js

import { describe, test } from "node:test";
import assert from "node:assert/strict";

describe("this is a simple test", () => {
  test("that this asserts", () => assert.equal(1, 1));

  test("return range", () => {
    const twoAmInAustralia = new Date("2023-05-13T02:00:00+10:00");
    const { from, until } = createRange(twoAmInAustralia);
    assert.equal(until.toISOString(), "2023-05-12T23:59:59.999Z");
    assert.equal(from.toISOString(), "2023-05-11T23:59:59.999Z"); // "at least 24 hours before until"
  });

  test("another date", () => {
    const noonInJapan = new Date("2023-05-13T01:00:00+09:00");
    const { from, until } = createRange(noonInJapan);
    assert.equal(until.toISOString(), "2023-05-12T23:59:59.999Z");
    assert.equal(from.toISOString(), "2023-05-11T23:59:59.999Z");
  });
});

/**
 * Give a local user date, returns a date range in UTC, where
 * - until is end of the UTC dat
 * - from is at least 24 hours before until
 */
const createRange = (userDate) => {
  const until = new Date(userDate);
  until.setUTCHours(23);
  until.setUTCMinutes(59);
  until.setUTCSeconds(59);
  until.setUTCMilliseconds(999);
  return { from: new Date(until.getTime() - 24 * 60 * 60 * 1000), until };
};