MCP Time Server Node

/** * Example of comprehensive time testing that would catch timezone edge cases * This test would have caught our daysUntil bug automatically! */ import { daysUntil } from '../../src/tools/daysUntil'; import { addDays, format } from 'date-fns'; import { testAtMultipleTimes, EDGE_TIMES, isLocalUTCDateDifferent } from '../utils/time-testing'; describe('Comprehensive Time Edge Case Testing', () => { /** * This is the test that would have caught our bug! * It tests the same operation at different times of day */ testAtMultipleTimes( 'daysUntil calculation', [ EDGE_TIMES.MIDNIGHT, EDGE_TIMES.NOON, EDGE_TIMES.LATE_EVENING, // This would catch our bug! EDGE_TIMES.JUST_BEFORE_MIDNIGHT, ], (currentTime) => { // Test adding 7 days at different times const futureDate = addDays(currentTime, 7); // The correct way (using format) const correctDateString = format(futureDate, 'yyyy-MM-dd'); const correctResult = daysUntil({ target_date: correctDateString }); // What our old tests were doing (using toISOString) const buggyDateString = futureDate.toISOString().split('T')[0]; const buggyResult = daysUntil({ target_date: buggyDateString }); // At noon, both would work // But at 11 PM, they'd differ! if (isLocalUTCDateDifferent(currentTime)) { console.log(`Found timezone boundary at ${currentTime}`); console.log(`Local date: ${format(currentTime, 'yyyy-MM-dd')}`); console.log(`UTC date: ${currentTime.toISOString().split('T')[0]}`); // The bug: these would be different expect(buggyResult).not.toBe(correctResult); } else { // When local and UTC are same day, both work expect(buggyResult).toBe(correctResult); } // The correct result should always be 7 expect(correctResult).toBe(7); }, ); /** * Property-based test: For ANY time, the calculation should be consistent */ it('should calculate days consistently regardless of time of day', () => { // Test 100 random times for (let i = 0; i < 100; i++) { const randomHour = Math.floor(Math.random() * 24); const randomMinute = Math.floor(Math.random() * 60); const testDate = new Date('2025-06-15'); // Middle of year, no DST issues testDate.setHours(randomHour, randomMinute, 0, 0); jest.setSystemTime(testDate); const futureDate = addDays(new Date(), 7); const dateString = format(futureDate, 'yyyy-MM-dd'); const result = daysUntil({ target_date: dateString }); expect(result).toBe(7); } }); /** * Chaos test: Randomly jump time during calculation */ it('should handle time changes during execution', () => { const startTime = new Date('2025-01-01T23:59:58'); // 2 seconds before midnight jest.setSystemTime(startTime); const futureDate = addDays(new Date(), 7); const dateString = format(futureDate, 'yyyy-MM-dd'); // Start calculation const result1 = daysUntil({ target_date: dateString }); // Time passes... it's now past midnight! jest.setSystemTime(new Date('2025-01-02T00:00:02')); // Same calculation should give same result // (because we're using the same target date string) const result2 = daysUntil({ target_date: dateString }); expect(result1).toBe(7); expect(result2).toBe(6); // One day has passed }); }); /** * Example: How to run tests in CI at different times */ describe('CI Time Matrix Testing', () => { // This would be configured in CI to actually run at these times const CI_TEST_TIMES = [ { time: '00:00', description: 'Midnight UTC' }, { time: '04:00', description: 'US East Coast midnight' }, { time: '08:00', description: 'US West Coast midnight' }, { time: '12:00', description: 'Noon UTC' }, { time: '23:59', description: 'Just before midnight UTC' }, ]; // In CI, we'd use a matrix strategy to run at each time it('documents when tests should run in CI', () => { console.log('Tests should run at these times in CI:'); CI_TEST_TIMES.forEach(({ time, description }) => { console.log(`- ${time} UTC: ${description}`); }); }); });