原生 Node.js 单元测试笔记

这两周都在写一个和项目相关的计算器，算是试行的一个测试驱动开发的模式，测试代码有写了几千行了，因为对于原生Node.js测试还不是很熟悉，有很多复制粘贴的代码，其中一个就是设计到debug模式。

import assert from "node:assert";
import { test } from "node:test";

export class Calculator {
	debug = false;

	constructor(options, debug = false) {
		this.debug = debug;
		this.options = options;
	}

	getTotal() {
		// Say we want to print out the options when we're in debug mode.
		if (!!this.debug) {
			console.log('options: ', this.options);
		}

		// Do some logic and return the total.
		return 234;
	}
}

test("Calculate", async (t) => {
	await t.test("Test case 1", () => {
		const options = {
			// ... some options.
		};
		const calculator = new Calculator(options, true);
		assert.strictEqual(calculator.getTotal(), 234);
	});

	await t.test("Test case 2", () => {
		const options = {
			// ... some options.
		};
		const calculator = new Calculator(options, true);
		assert.strictEqual(calculator.getTotal(), 234);
	});

	await t.test("Test case 3", () => {
		const options = {
			// ... some options.
		};
		const calculator = new Calculator(options);
		assert.strictEqual(calculator.getTotal(), 234);
	});
});

非常简单的一个例子，假如我们的测试非常多时，每次传入debug=true第二个参数有点繁琐，我想的是可以创建一个factory函数来简化。

import assert from "node:assert";
import { test } from "node:test";

export class Calculator {
	debug = false;

	constructor(options, debug = false) {
		this.debug = debug;
		this.options = options;
	}

	getTotal() {
		// Say we want to print out the options when we're in debug mode.
		if (!!this.debug) {
			console.log('options: ', this.options);
		}

		// Do some logic and return the total.
		return 234;
	}
}

function createCalculatorWithDebug(options) {
	return new Calculator(options, true);
}

test("Calculate", async (t) => {
	await t.test("Test case 1", () => {
		const options = {
			// ... some options.
		};
		const calculator = createCalculatorWithDebug(options);
		assert.strictEqual(calculator.getTotal(), 234);
	});

	await t.test("Test case 2", () => {
		const options = {
			// ... some options.
		};
		const calculator = createCalculatorWithDebug(options);
		assert.strictEqual(calculator.getTotal(), 234);
	});

	await t.test("Test case 3", () => {
		const options = {
			// ... some options.
		};
		const calculator = createCalculatorWithDebug(options);
		assert.strictEqual(calculator.getTotal(), 234);
	});
});

assert.strictEqual(calculator.calculate(selections[0], selections[1], amount, true), 0);

当重构代码时，可能会将得出总数的函数改为calculator.getResult()，那么测试文件中所有的函数都要修改。

assert.strictEqual(calculator.calculate(selections[0], selections[1], amount, true), 0); 
// 改成
assert.strictEqual(calculator.getResult(), 0);