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

Algorithms and data-structures implemented on JavaScript

"use strict";

var _SimplePolynomialHash = _interopRequireDefault(require("../SimplePolynomialHash"));

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

describe('PolynomialHash', () => {
  it('should calculate new hash based on previous one', () => {
    const bases = [3, 5];
    const frameSizes = [5, 10];
    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 1960s with the release of Letraset sheets ' + 'publishing software like Aldus 耀 PageMaker including versions of Lorem.'; // Check hashing for different prime base.

    bases.forEach(base => {
      const polynomialHash = new _SimplePolynomialHash.default(base); // 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', () => {
    const polynomialHash = new _SimplePolynomialHash.default();
    expect(polynomialHash.hash('Test')).toBe(604944);
    expect(polynomialHash.hash('a')).toBe(97);
    expect(polynomialHash.hash('b')).toBe(98);
    expect(polynomialHash.hash('c')).toBe(99);
    expect(polynomialHash.hash('d')).toBe(100);
    expect(polynomialHash.hash('e')).toBe(101);
    expect(polynomialHash.hash('ab')).toBe(1763);
    expect(polynomialHash.hash('abc')).toBe(30374);
  });
});