foo.js

it('"moveRight()" should increment the "x" propety by 1', function () {
  var blocky = new Block(15, 30);
  blocky.moveRight();
  assert.equal(blocky.x, 16);
});

//....vs....

it('"moveRight()" should increment the "x" propety by 1', function () {
  var startingX = 15;
  var endingX = startingX + 1;
  
  var blocky = new Block(startingX, 30);
  blocky.moveRight();
  
  assert.equal(blocky.x, endingX);
});