// 公有函數add
function add(a, b)
{
    return a + b;
}

// 私有函數sub
function sub(a, b)
{
	return a - b;
}

exports.add = add;

// 測試公有函數add
var assert  = require("assert");
var add = require("../test1.js").add;

it("1加1等於2", function()
{
    var result = add(1, 1);
    assert.equal(result, 2);
});
 

// 測試私有函數sub
var assert  = require("assert");
var rewire = require("rewire");
var sub = rewire("../test1.js").__get__("sub");

it("2減1等於1", function()
{
    var result = sub(2, 1);
    assert.equal(result, 1);
});

var fs = require("fs")

function add(a, b)
{
    let result = a + b;
    fs.writeFileSync("result.txt", result);
    return result;
}

exports.add = add;

var assert = require("assert");
var add = require("../test2.js").add;

it("1加1等於2", function()
{
    let result = add(1, 2);
    assert.equal(result, 3);
});

var assert = require("assert");
var rewire = require("rewire");
var myModule = rewire("../test2.js")
var add = myModule.add;

var fsMock = {
    writeFileSync: function(file, data, option) { /* 啥也不幹 */ }
};

myModule.__set__("fs", fsMock);

it("1加1等於2", function()
{
    let result = add(1, 2);
    assert.equal(result, 3);
});