nepali-date-converter-np/tests/conversion.test.ts

A lightweight TypeScript/JavaScript package for converting dates between Gregorian (AD) and Bikram Sambat (BS) calendar systems with Nepali and English formatting support.

import { convertADToBS, convertBSToAD, BSDate, ADDate } from '../src/index';

describe('Date Conversion Tests', () => {
  describe('convertADToBS', () => {
    test('should convert known AD date to BS correctly', () => {
      // Known mapping: 1943-04-14 AD = 2000-01-01 BS
      const adDate: ADDate = { year: 1943, month: 4, day: 14 };
      const expected: BSDate = { year: 2000, month: 1, day: 1 };
      
      const result = convertADToBS(adDate);
      expect(result).toEqual(expected);
    });

    test('should convert AD date within supported range', () => {
      // Test a date in the middle of supported range
      const adDate: ADDate = { year: 1944, month: 6, day: 15 };
      const result = convertADToBS(adDate);
      
      expect(result.year).toBeGreaterThanOrEqual(2000);
      expect(result.year).toBeLessThanOrEqual(2002);
      expect(result.month).toBeGreaterThanOrEqual(1);
      expect(result.month).toBeLessThanOrEqual(12);
      expect(result.day).toBeGreaterThanOrEqual(1);
      expect(result.day).toBeLessThanOrEqual(32);
    });

    test('should handle leap year conversion', () => {
      // Test conversion around leap year
      const adDate: ADDate = { year: 1944, month: 2, day: 29 };
      const result = convertADToBS(adDate);
      
      expect(result).toBeDefined();
      expect(typeof result.year).toBe('number');
      expect(typeof result.month).toBe('number');
      expect(typeof result.day).toBe('number');
    });

    test('should throw error for unsupported AD date range', () => {
      // Test date outside supported range
      const adDate: ADDate = { year: 2021, month: 10, day: 10 };
      
      expect(() => convertADToBS(adDate)).toThrow();
    });
  });

  describe('convertBSToAD', () => {
    test('should convert known BS date to AD correctly', () => {
      // Known mapping: 2000-01-01 BS = 1943-04-14 AD
      const bsDate: BSDate = { year: 2000, month: 1, day: 1 };
      const expected: ADDate = { year: 1943, month: 4, day: 14 };
      
      const result = convertBSToAD(bsDate);
      expect(result).toEqual(expected);
    });

    test('should convert BS date within supported range', () => {
      // Test a date in the middle of supported range
      const bsDate: BSDate = { year: 2001, month: 6, day: 15 };
      const result = convertBSToAD(bsDate);
      
      expect(result.year).toBeGreaterThanOrEqual(1943);
      expect(result.year).toBeLessThanOrEqual(1945);
      expect(result.month).toBeGreaterThanOrEqual(1);
      expect(result.month).toBeLessThanOrEqual(12);
      expect(result.day).toBeGreaterThanOrEqual(1);
      expect(result.day).toBeLessThanOrEqual(31);
    });

    test('should handle month transitions correctly', () => {
      // Test conversion at month boundaries
      const bsDate: BSDate = { year: 2000, month: 12, day: 31 };
      const result = convertBSToAD(bsDate);
      
      expect(result).toBeDefined();
      expect(typeof result.year).toBe('number');
      expect(typeof result.month).toBe('number');
      expect(typeof result.day).toBe('number');
    });

    test('should throw error for unsupported BS date range', () => {
      // Test date outside supported range
      const bsDate: BSDate = { year: 2078, month: 6, day: 24 };
      
      expect(() => convertBSToAD(bsDate)).toThrow();
    });
  });

  describe('Round-trip conversion', () => {
    test('should maintain consistency in round-trip conversion', () => {
      const originalAD: ADDate = { year: 1944, month: 8, day: 15 };
      
      const bsDate = convertADToBS(originalAD);
      const convertedAD = convertBSToAD(bsDate);
      
      expect(convertedAD).toEqual(originalAD);
    });

    test('should handle edge cases in round-trip conversion', () => {
      const originalAD: ADDate = { year: 1943, month: 12, day: 31 };
      
      const bsDate = convertADToBS(originalAD);
      const convertedAD = convertBSToAD(bsDate);
      
      expect(convertedAD).toEqual(originalAD);
    });
  });

  describe('Input validation', () => {
    test('should handle invalid month values', () => {
      const invalidAD: ADDate = { year: 1944, month: 13, day: 1 };
      
      expect(() => convertADToBS(invalidAD)).toThrow();
    });

    test('should handle invalid day values', () => {
      const invalidAD: ADDate = { year: 1944, month: 2, day: 32 };
      
      expect(() => convertADToBS(invalidAD)).toThrow();
    });

    test('should handle zero values', () => {
      const invalidAD: ADDate = { year: 1944, month: 0, day: 0 };
      
      expect(() => convertADToBS(invalidAD)).toThrow();
    });
  });
});