nes-emu/ppu/registers/PPUCtrl.spec.js

A NES emulator

"use strict";

var _createTestContext = _interopRequireDefault(require("../../helpers/createTestContext"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const should = require("chai").Should();
const ADDRESS = 0x2000;
describe("CPU/PPU registers interaction", () => {
  describe("PPUCtrl", () => {
    let ppu, memory, register;
    beforeEach(() => {
      ({
        ppu,
        memory
      } = (0, _createTestContext.default)());
      register = ppu.registers.ppuCtrl;
    });
    it("is write-only", () => {
      memory.writeAt(ADDRESS, 120);
      register.value.should.equal(120);
      memory.readAt(ADDRESS).should.equal(0);
    });
    it("can return the VRAM address increment", () => {
      memory.writeAt(ADDRESS, 0b00000000);
      register.vramAddressIncrement.should.equal(1);
      memory.writeAt(ADDRESS, 0b00000100);
      register.vramAddressIncrement.should.equal(32);
    });
    it("provides the sprite mode", () => {
      memory.writeAt(ADDRESS, 0b00000000);
      register.isIn8x16Mode.should.equal(false);
      memory.writeAt(ADDRESS, 0b00100000);
      register.isIn8x16Mode.should.equal(true);
    });
  });
});