nes-emu/ppu/registers/PPUScroll.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 = 0x2005;
describe("CPU/PPU registers interaction", () => {
  describe("PPUScroll", () => {
    let ppu, memory, register;
    beforeEach(() => {
      ({
        ppu,
        memory
      } = (0, _createTestContext.default)());
      register = ppu.registers.ppuScroll;
    });
    it("is write-only", () => {
      register.setValue(123);
      memory.readAt(ADDRESS).should.equal(0);
    });
    it("writes X first, then Y", () => {
      memory.writeAt(ADDRESS, 13);
      memory.writeAt(ADDRESS, 58);

      // (copy temporal address to current address)
      ppu.loopy._copyX();
      ppu.loopy._copyY();
      register.scrolledX(0).should.equal(13);
      register.scrolledY().should.equal(58);
    });
  });
});