dist-javascript-algorithms-and-data-structures/dist/algorithms/cryptography/polynomial-hash/__test__/PolynomialHash.test.js

Algorithms and data-structures implemented on JavaScript

"use strict";

var _PolynomialHash = _interopRequireDefault(require("../PolynomialHash"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

describe('PolynomialHash', () => {
  it('should calculate new hash based on previous one', () => {
    const bases = [3, 79, 101, 3251, 13229, 122743, 3583213];
    const mods = [79, 101];
    const frameSizes = [5, 20]; // @TODO: Provide Unicode support.

    const text = 'Lorem Ipsum is simply dummy text of the printing and ' + 'typesetting industry. Lorem Ipsum has been the industry\'s standard ' + 'galley of type and \u{ffff} scrambled it to make a type specimen book. It ' + 'electronic 耀 typesetting, remaining essentially unchanged. It was ' // + 'popularised in the \u{20005} \u{20000}1960s with the release of Letraset sheets '
    + 'publishing software like Aldus PageMaker 耀 including versions of Lorem.'; // Check hashing for different prime base.

    bases.forEach(base => {
      mods.forEach(modulus => {
        const polynomialHash = new _PolynomialHash.default({
          base,
          modulus
        }); // Check hashing for different word lengths.

        frameSizes.forEach(frameSize => {
          let previousWord = text.substr(0, frameSize);
          let previousHash = polynomialHash.hash(previousWord); // Shift frame through the whole text.

          for (let frameShift = 1; frameShift < text.length - frameSize; frameShift += 1) {
            const currentWord = text.substr(frameShift, frameSize);
            const currentHash = polynomialHash.hash(currentWord);
            const currentRollingHash = polynomialHash.roll(previousHash, previousWord, currentWord); // Check that rolling hash is the same as directly calculated hash.

            expect(currentRollingHash).toBe(currentHash);
            previousWord = currentWord;
            previousHash = currentHash;
          }
        });
      });
    });
  });
  it('should generate numeric hashed less than 100', () => {
    const polynomialHash = new _PolynomialHash.default({
      modulus: 100
    });
    expect(polynomialHash.hash('Some long text that is used as a key')).toBe(41);
    expect(polynomialHash.hash('Test')).toBe(92);
    expect(polynomialHash.hash('a')).toBe(97);
    expect(polynomialHash.hash('b')).toBe(98);
    expect(polynomialHash.hash('c')).toBe(99);
    expect(polynomialHash.hash('d')).toBe(0);
    expect(polynomialHash.hash('e')).toBe(1);
    expect(polynomialHash.hash('ab')).toBe(87); // @TODO: Provide Unicode support.

    expect(polynomialHash.hash('\u{20000}')).toBe(92);
  });
});