meteor/packages/random/random_tests.js

import { Meteor } from 'meteor/meteor';
import { Random } from 'meteor/random';

Tinytest.add('random', function (test) {
  // Deterministic with a specified seed, which should generate the
  // same sequence in all environments.
  //
  // For repeatable unit test failures using deterministic random
  // number sequences it's fine if a new Meteor release changes the
  // algorithm being used and it starts generating a different
  // sequence for a seed, as long as the sequence is consistent for
  // a particular release.
  const random = Random.createWithSeeds(0);
  test.equal(random.id(), 'cp9hWvhg8GSvuZ9os');
  test.equal(random.id(), '3f3k6Xo7rrHCifQhR');
  test.equal(random.id(), 'shxDnjWWmnKPEoLhM');
  test.equal(random.id(), '6QTjB8C5SEqhmz4ni');
});

// node crypto and window.crypto.getRandomValues() don't let us specify a seed,
// but at least test that the output is in the right format.
Tinytest.add('random - format', function (test) {
  const idLen = 17;
  test.equal(Random.id().length, idLen);
  test.equal(Random.id(29).length, 29);
  const numDigits = 9;
  const hexStr = Random.hexString(numDigits);
  test.equal(hexStr.length, numDigits);
  Number.parseInt(hexStr, 16); // should not throw
  const frac = Random.fraction();
  test.isTrue(frac < 1.0);
  test.isTrue(frac >= 0.0);

  test.equal(Random.secret().length, 43);
  test.equal(Random.secret(13).length, 13);
});

Tinytest.add('random - Alea is last resort', function (test) {
  if (Meteor.isServer) {
    test.isTrue(Random.alea === undefined);
  }
  if (Meteor.isClient) {
    const useGetRandomValues = !!(typeof window !== 'undefined' &&
        window.crypto && window.crypto.getRandomValues);
    test.equal(Random.alea === undefined, useGetRandomValues);
  }
});

Tinytest.add('random - createWithSeeds requires parameters', function (test) {
  test.throws(function () {
    Random.createWithSeeds();
  });
});