在 重构：改善既有代码的设计 (第2版) 中，构筑测试体系 – 待测试的示例代码的编写
1、一份有待测试的代码。这份代码来自一个简单的应用，用于支持用户查看并调整生产计划。它的（略显粗糙的）界面长得像下面这张图所示的这样。如图1
图1
2、示例代码最终实现如下，入口的 productionPlan.html 文件代码如下
<!DOCTYPE html>
<html lang="en-US">
<head>
<meta charset="utf-8">
<title>构筑测试体系 - 待测试的示例代码</title>
<style>
</style>
<script type="module" src="productionPlan.js"></script>
</head>
<body>
</body>
</html>
3、引入的模块 productionPlan.js 文件代码如下
function sampleProvinceData() {
return {
name: "Asia",
producers: [
{name: "Byzantium", cost: 10, production: 9},
{name: "Attalia", cost: 12, production: 10},
{name: "Sinope", cost: 10, production: 6},
],
demand: 30,
price: 20
};
}
class Province {
constructor(doc) {
this._name = doc.name;
this._producers = [];
this._totalProduction = 0;
this._demand = doc.demand;
this._price = doc.price;
doc.producers.forEach(d => this.addProducer(new Producer(this, d)));
}
addProducer(arg) {
this._producers.push(arg);
this._totalProduction += arg.production;
}
get name() {
return this._name;
}
get producers() {
return this._producers.slice();
}
get totalProduction() {
return this._totalProduction;
}
set totalProduction(arg) {
this._totalProduction = arg;
}
get demand() {
return this._demand;
}
set demand(arg) {
this._demand = parseInt(arg);
}
get price() {
return this._price;
}
set price(arg) {
this._price = parseInt(arg);
}
get shortfall() {
return this._demand - this.totalProduction;
}
get profit() {
return this.demandValue - this.demandCost;
}
get demandCost() {
let remainingDemand = this.demand;
let result = 0;
this.producers
.sort((a, b) => a.cost - b.cost)
.forEach(p => {
const contribution = Math.min(remainingDemand, p.production);
remainingDemand -= contribution;
result += contribution * p.cost;
});
return result;
}
get demandValue() {
return this.satisfiedDemand * this.price;
}
get satisfiedDemand() {
return Math.min(this._demand, this.totalProduction);
}
}
class Producer {
constructor(aProvince, data) {
this._province = aProvince;
this._cost = data.cost;
this._name = data.name;
this._production = data.production || 0;
}
get name() {
return this._name;
}
get cost() {
return this._cost;
}
set cost(arg) {
this._cost = parseInt(arg);
}
get production() {
return this._production;
}
set production(amountStr) {
const amount = parseInt(amountStr);
const newProduction = Number.isNaN(amount) ? 0 : amount;
this._province.totalProduction += newProduction - this._production;
this._production = newProduction;
}
}
const asia = new Province(sampleProvinceData());
console.log(asia.shortfall);
3、代码 const asia = new Province(sampleProvinceData()); 参考：4.3 第一个测试示例。如图2
图2
4、在浏览器中打开：http://localhost/refactoring/4/productionPlan.html ，查看控制台输出：5，符合预期。如图3
图3
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