support_backend/tests/unit/platform/business-calendars/calendar-walk.test.ts

import { describe, it, expect } from 'vitest';
import { addBusinessMinutes, isWithinWorkingHours } from '@/modules/platform/business-calendars/calculators/business-hours.calculator';

const MON_FRI_9_TO_5 = {
  timezone: 'America/New_York',
  workingHours: {
    mon: { start: '09:00', end: '17:00' },
    tue: { start: '09:00', end: '17:00' },
    wed: { start: '09:00', end: '17:00' },
    thu: { start: '09:00', end: '17:00' },
    fri: { start: '09:00', end: '17:00' },
  },
};

// America/New_York is UTC-5 (EST) outside DST, UTC-4 (EDT) during DST — every Date.UTC(...)
// below is written as the equivalent UTC instant for the Eastern wall-clock time noted in the
// comment, since luxon's own DST handling is exactly what's under test here.

describe('addBusinessMinutes', () => {
  it('stays within the same working day when enough time remains', () => {
    // Mon 2026-01-05 10:00 EST (UTC-5) -> 15:00 UTC
    const start = new Date(Date.UTC(2026, 0, 5, 15, 0));
    const due = addBusinessMinutes(start, 120, MON_FRI_9_TO_5, []);
    // +120 min -> 12:00 EST -> 17:00 UTC
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 0, 5, 17, 0)).toISOString());
  });

  it('rolls over a weekend, never counting Saturday/Sunday as available time', () => {
    // Fri 2026-01-02 16:00 EST (1 hour left in the window) -> 21:00 UTC
    const start = new Date(Date.UTC(2026, 0, 2, 21, 0));
    // 1 hour left Friday + need 3 more hours -> Monday 12:00 EST
    const due = addBusinessMinutes(start, 240, MON_FRI_9_TO_5, []);
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 0, 5, 17, 0)).toISOString()); // Mon 12:00 EST
  });

  it('excludes a holiday entirely, rolling to the next working day', () => {
    // Fri 2026-01-02 16:00 EST, Monday Jan 5 is a holiday
    const start = new Date(Date.UTC(2026, 0, 2, 21, 0));
    const holiday = new Date(Date.UTC(2026, 0, 5, 17, 0)); // Mon 12:00 EST — safely mid-Monday
    const due = addBusinessMinutes(start, 240, MON_FRI_9_TO_5, [holiday]);
    // 1h Friday + Monday excluded + 3h into Tuesday -> Tue 12:00 EST
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 0, 6, 17, 0)).toISOString());
  });

  it('a weekday with no configured window contributes zero available time', () => {
    const noWednesday = {
      timezone: 'America/New_York',
      workingHours: {
        tue: { start: '09:00', end: '17:00' },
        thu: { start: '09:00', end: '17:00' },
      },
    };
    // Tue 2026-01-06 16:00 EST (1h left)
    const start = new Date(Date.UTC(2026, 0, 6, 21, 0));
    const due = addBusinessMinutes(start, 300, noWednesday, []);
    // 1h Tue + (Wed skipped, zero hours) + 4h into Thu -> Thu 13:00 EST
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 0, 8, 18, 0)).toISOString());
  });

  it('clips to the start time on the first day, never counting time before it', () => {
    // Mon 10:00 EST: 7h remain in the window (to 17:00) + 1 more hour -> Tue 10:00 EST
    const start = new Date(Date.UTC(2026, 0, 5, 15, 0));
    const due = addBusinessMinutes(start, 420 + 60, MON_FRI_9_TO_5, []);
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 0, 6, 15, 0)).toISOString()); // Tue 10:00 EST
  });

  it('returns the start time unchanged when minutes is zero or negative', () => {
    const start = new Date(Date.UTC(2026, 0, 5, 15, 0));
    expect(addBusinessMinutes(start, 0, MON_FRI_9_TO_5, []).toISOString()).toBe(start.toISOString());
  });

  it('is correct across a DST transition (US spring-forward, March 2026)', () => {
    // 2026-03-08 is the US DST transition (02:00 -> 03:00). Fri 2026-03-06 16:00 EST (1h left).
    const start = new Date(Date.UTC(2026, 2, 6, 21, 0));
    // 1h Friday + weekend skipped + 3h into Monday 2026-03-09 (now EDT, UTC-4) -> 12:00 EDT -> 16:00 UTC
    const due = addBusinessMinutes(start, 240, MON_FRI_9_TO_5, []);
    expect(due.toISOString()).toBe(new Date(Date.UTC(2026, 2, 9, 16, 0)).toISOString());
  });
});

describe('isWithinWorkingHours', () => {
  it('is true inside a configured window and false outside it', () => {
    const insideWindow = new Date(Date.UTC(2026, 0, 5, 16, 0)); // Mon 11:00 EST
    const beforeWindow = new Date(Date.UTC(2026, 0, 5, 13, 0)); // Mon 08:00 EST
    expect(isWithinWorkingHours(insideWindow, MON_FRI_9_TO_5, [])).toBe(true);
    expect(isWithinWorkingHours(beforeWindow, MON_FRI_9_TO_5, [])).toBe(false);
  });

  it('is false on a weekend and on a holiday', () => {
    const saturday = new Date(Date.UTC(2026, 0, 3, 16, 0));
    expect(isWithinWorkingHours(saturday, MON_FRI_9_TO_5, [])).toBe(false);

    const mondayNoon = new Date(Date.UTC(2026, 0, 5, 16, 0)); // Mon 11:00 EST
    const holiday = new Date(Date.UTC(2026, 0, 5, 17, 0)); // Mon 12:00 EST — safely mid-Monday
    expect(isWithinWorkingHours(mondayNoon, MON_FRI_9_TO_5, [holiday])).toBe(false);
  });
});