random generator for tests

test.js

var Random = function() {
  var s1 = 1243598713, s2 = 3093459404, s3 = 1821928721;
  return function() {
    s1 = ((s1 & 4294967294) << 12) ^ (((s1 << 13) ^  s1) >>> 19);
    s2 = ((s2 & 4294967288) <<  4) ^ (((s2 <<  2) ^  s2) >>> 25);
    s3 = ((s3 & 4294967280) << 17) ^ (((s3 <<  3) ^  s3) >>> 11);
    return ((s1 ^ s2 ^ s3) >>> 0) / 4294967296;
  };
};

describe("random", function() {
  var _random = Math.random;
  beforeEach(function() {
    Math.random = new Random();
  });
  afterEach(function() {
    Math.random = _random;
  });
  it("coin", function() {
    var coin = Math.random();
    assert.ok(coin > 0.5);
  });
});