MCP Time Server Node

import { daysUntil } from '../../src/tools/daysUntil'; import { getBusinessDays } from '../../src/tools/getBusinessDays'; import { addDays, format } from 'date-fns'; describe('Timezone Boundary Edge Cases', () => { describe('when local date differs from UTC date', () => { beforeEach(() => { // Simulate late evening in Eastern time (already next day in UTC) // July 28 at 11 PM EDT = July 29 at 3 AM UTC jest.useFakeTimers(); jest.setSystemTime(new Date('2025-07-28T23:00:00-04:00')); }); afterEach(() => { jest.useRealTimers(); }); it('daysUntil should use consistent timezone for date math', () => { const futureDate = addDays(new Date(), 7); // Using toISOString() would give us the UTC date (wrong!) const wrongDateString = futureDate.toISOString().split('T')[0]; // '2025-08-05' // Using format() gives us the local date (correct!) const correctDateString = format(futureDate, 'yyyy-MM-dd'); // '2025-08-04' // The bug: using ISO string causes off-by-one error expect(daysUntil({ target_date: wrongDateString })).toBe(8); // Bug! expect(daysUntil({ target_date: correctDateString })).toBe(7); // Correct! }); it('should handle "today" correctly across timezone boundary', () => { const localToday = format(new Date(), 'yyyy-MM-dd'); // '2025-07-28' const utcToday = new Date().toISOString().split('T')[0]; // '2025-07-29' expect(daysUntil({ target_date: localToday })).toBe(0); // Today (correct) expect(daysUntil({ target_date: utcToday })).toBe(1); // Tomorrow (wrong!) }); it('business days calculation should handle timezone boundaries', () => { const start = format(new Date(), 'yyyy-MM-dd'); const end = format(addDays(new Date(), 5), 'yyyy-MM-dd'); const result = getBusinessDays({ start_date: start, end_date: end, exclude_weekends: true, }); // Should get consistent results regardless of time of day expect(result.business_days).toBeGreaterThan(0); }); }); describe('DST transition edge cases', () => { beforeEach(() => { jest.useFakeTimers(); }); afterEach(() => { jest.useRealTimers(); }); it('should handle spring forward correctly', () => { // March 9, 2025 at 2 AM EST -> 3 AM EDT (lose an hour) jest.setSystemTime(new Date('2025-03-09T01:59:59-05:00')); const beforeDST = format(new Date(), 'yyyy-MM-dd'); // Jump to after DST transition jest.setSystemTime(new Date('2025-03-09T03:00:01-04:00')); // Should still be the same day expect(daysUntil({ target_date: beforeDST })).toBe(0); }); it('should handle fall back correctly', () => { // November 2, 2025 at 2 AM EDT -> 1 AM EST (gain an hour) jest.setSystemTime(new Date('2025-11-02T01:59:59-04:00')); const beforeDST = format(new Date(), 'yyyy-MM-dd'); // Jump to after DST transition jest.setSystemTime(new Date('2025-11-02T01:00:01-05:00')); const afterDST = format(new Date(), 'yyyy-MM-dd'); // Should still be the same day expect(beforeDST).toBe(afterDST); }); }); describe('Year and month boundaries', () => { beforeEach(() => { jest.useFakeTimers(); }); afterEach(() => { jest.useRealTimers(); }); it('should handle year transition correctly', () => { // December 31, 2026 at 11:59 PM jest.setSystemTime(new Date('2026-12-31T23:59:59')); const todayResult = daysUntil({ target_date: '2026-12-31' }); const tomorrowResult = daysUntil({ target_date: '2027-01-01' }); expect(todayResult).toBe(0); expect(tomorrowResult).toBe(1); }); it('should handle leap year correctly', () => { // February 28, 2028 (leap year) jest.setSystemTime(new Date('2028-02-28T12:00:00')); const feb29Result = daysUntil({ target_date: '2028-02-29' }); const mar1Result = daysUntil({ target_date: '2028-03-01' }); expect(feb29Result).toBe(1); expect(mar1Result).toBe(2); }); }); });