nes-emu/cpu/registers/Register.spec.js

A NES emulator

"use strict";

var _ = require(".");
const should = require("chai").Should();
describe("registers", () => {
  describe("Register8Bit", () => {
    it("allows initial values", () => {
      const register = new _.Register8Bit(5);
      register.value.should.equal(5);
      register.value = 8;
      register.value.should.equal(8);
      register.reset();
      register.value.should.equal(5);
    });
    it("handles overflows and underflows correctly", () => {
      const register = new _.Register8Bit(250);
      register.value += 7;
      register.value.should.equal(1);
      register.value = 0;
      register.value--;
      register.value.should.equal(255);
    });
    it("can increment the value", () => {
      const register = new _.Register8Bit(250);
      register.increment();
      register.value.should.equal(251);
    });
    it("can decrement the value", () => {
      const register = new _.Register8Bit(250);
      register.decrement();
      register.value.should.equal(249);
    });
  });
});