nes-emu/memory/MemoryChunk.spec.js

A NES emulator

"use strict";

var _MemoryChunk = _interopRequireDefault(require("./MemoryChunk"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const should = require("chai").Should();
describe("memory", () => {
  describe("MemoryChunk", () => {
    let buffer, chunk;
    beforeEach(() => {
      buffer = new Uint8Array(5);
      chunk = new _MemoryChunk.default(buffer, 29);
    });
    it("can create a chunk just passing the number of bytes", () => {
      new _MemoryChunk.default(5).bytes.length.should.equal(5);
    });
    it("can write and read bytes", () => {
      chunk.writeAt(2, 123);
      chunk.readAt(2).should.equal(123);
    });
    it("can read and write numbers in Little Endian", () => {
      chunk.writeAt(0, 0x20);
      chunk.writeAt(1, 0xff);
      chunk.write2BytesAt(2, 0xfe30);
      chunk.readBytesAt(0, 1).should.equal(0x20);
      chunk.readBytesAt(1, 1).should.equal(0xff);
      chunk.readBytesAt(0, 2).should.equal(0xff20);
      chunk.read2BytesAt(0).should.equal(0xff20);
      chunk.read2BytesAt(2).should.equal(0xfe30);
    });
    it("can return the size of the buffer", () => {
      chunk.memorySize.should.equal(5);
    });
    it("ignores write operations when the read only flag is active", () => {
      const chunk = new _MemoryChunk.default(5).asReadOnly();
      chunk.writeAt(1, 25);
      chunk.bytes[1].should.equal(0);
      chunk.asReadOnly(false);
      chunk.writeAt(1, 26);
      chunk.bytes[1].should.equal(26);
    });
    it("throws an exception when the address is out of bounds", () => {
      (() => chunk.writeAt(9, 123)).should.throw("Invalid memory access at 0x9");
    });
  });
});