nes-emu/ppu/registers/PPUMask.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 = 0x2001;
describe("CPU/PPU registers interaction", () => {
  describe("PPUMask", () => {
    let ppu, memory, register;
    beforeEach(() => {
      ({
        ppu,
        memory
      } = (0, _createTestContext.default)());
      register = ppu.registers.ppuMask;
    });
    it("is write-only", () => {
      memory.writeAt(ADDRESS, 123);
      register.value.should.equal(123);
      memory.readAt(ADDRESS).should.equal(0);
    });
    it("can write the register", () => {
      register.showBackground.should.equal(0);
      register.emphasizeRed.should.equal(0);
      register.showSprites.should.equal(0);
      register.emphasizeGreen.should.equal(0);
      memory.writeAt(ADDRESS, 0b00101000);
      register.showBackground.should.equal(1);
      register.emphasizeRed.should.equal(1);
      register.showSprites.should.equal(0);
      register.emphasizeGreen.should.equal(0);
    });
    describe("transform", () => {
      it("returns the same color if no transformation is applied", () => {
        register.transform(0xe821d9).should.equal(0xe821d9);
      });
      it("can transform a color to grayscale", () => {
        register.grayscale = 1;
        register.transform(0xc72631).should.equal(0x5e5e5e);
      });
      it("can transform a color emphasizing red", () => {
        register.emphasizeRed = 1;
        register.transform(0xc72631).should.equal(0x951c31);
      });
      it("can transform a color emphasizing green", () => {
        register.emphasizeGreen = 1;
        register.transform(0xc72631).should.equal(0x952624);
      });
      it("can transform a color emphasizing blue", () => {
        register.emphasizeBlue = 1;
        register.transform(0xc72631).should.equal(0xc71c24);
      });
      it("can emphasize two colors at the same time", () => {
        register.emphasizeRed = 1;
        register.emphasizeBlue = 1;
        register.transform(0xc72631).should.equal(0xc71c31);
      });
      it("applies emphasis bits independently of grayscale", () => {
        register.grayscale = 1;
        register.emphasizeRed = 1;
        register.emphasizeBlue = 1;
        register.transform(0xc72631).should.equal(0x5e465e);
      });
    });
  });
});