get-string-permutations.test.js

const { getPermutations } = require('.');

describe('Get permutations of a string', () => {
  it('returns permutations of a short string', () => {
    const shortString = 'ab';
    const expectedPermutations = ['ab', 'ba'];

    expect(getPermutations(shortString)).toEqual(expectedPermutations);
  });

  it('returns permutations of a long string', () => {
    const shortString = 'XUNDA';
    const expectedPermutations = [
      'XUNDA',
      'UXNDA',
      'NXUDA',
      'XNUDA',
      'UNXDA',
      'NUXDA',
      'DUXNA',
      'UDXNA',
      'XDUNA',
      'DXUNA',
      'UXDNA',
      'XUDNA',
      'XNDUA',
      'NXDUA',
      'DXNUA',
      'XDNUA',
      'NDXUA',
      'DNXUA',
      'DNUXA',
      'NDUXA',
      'UDNXA',
      'DUNXA',
      'NUDXA',
      'UNDXA',
      'ANDXU',
      'NADXU',
      'DANXU',
      'ADNXU',
      'NDAXU',
      'DNAXU',
      'XNADU',
      'NXADU',
      'AXNDU',
      'XANDU',
      'NAXDU',
      'ANXDU',
      'ADXNU',
      'DAXNU',
      'XADNU',
      'AXDNU',
      'DXANU',
      'XDANU',
      'XDNAU',
      'DXNAU',
      'NXDAU',
      'XNDAU',
      'DNXAU',
      'NDXAU',
      'UDXAN',
      'DUXAN',
      'XUDAN',
      'UXDAN',
      'DXUAN',
      'XDUAN',
      'ADUXN',
      'DAUXN',
      'UADXN',
      'AUDXN',
      'DUAXN',
      'UDAXN',
      'UXADN',
      'XUADN',
      'AUXDN',
      'UAXDN',
      'XAUDN',
      'AXUDN',
      'AXDUN',
      'XADUN',
      'DAXUN',
      'ADXUN',
      'XDAUN',
      'DXAUN',
      'NXAUD',
      'XNAUD',
      'ANXUD',
      'NAXUD',
      'XANUD',
      'AXNUD',
      'UXNAD',
      'XUNAD',
      'NUXAD',
      'UNXAD',
      'XNUAD',
      'NXUAD',
      'NAUXD',
      'ANUXD',
      'UNAXD',
      'NUAXD',
      'AUNXD',
      'UANXD',
      'UAXND',
      'AUXND',
      'XUAND',
      'UXAND',
      'AXUND',
      'XAUND',
      'DAUNX',
      'ADUNX',
      'UDANX',
      'DUANX',
      'AUDNX',
      'UADNX',
      'NADUX',
      'ANDUX',
      'DNAUX',
      'NDAUX',
      'ADNUX',
      'DANUX',
      'DUNAX',
      'UDNAX',
      'NDUAX',
      'DNUAX',
      'UNDAX',
      'NUDAX',
      'NUADX',
      'UNADX',
      'ANUDX',
      'NAUDX',
      'UANDX',
      'AUNDX',
    ];

    expect(getPermutations(shortString).sort()).toEqual(expectedPermutations.sort());
  });

  it('returns the same string if the string is one character long', () => {
    const shortString = 'a';
    const expectedPermutations = ['a'];

    expect(getPermutations(shortString)).toEqual(expectedPermutations);
  });

  it('returns an empty array for an empty string', () => {
    const shortString = '';
    const expectedPermutations = [];

    expect(getPermutations(shortString)).toEqual(expectedPermutations);
  });

  it('is case sensitive', () => {
    const shortString = 'aB';

    expect(getPermutations(shortString)).not.toEqual(['ab', 'ba']);
    expect(getPermutations(shortString)).toEqual(['aB', 'Ba']);
  });
});