June 2021
Intermediate to advanced
290 pages
9h 21m
Chinese
Content preview from Node与Express开发（第2版）
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44
｜
第
5
章
东西拼接了起来。给
Express
配置有关的中间件，然后启动服务。不用说要有效测试这些
代码有多困难，就说不必测试也是合理的理由，因为它只是把经过良好测试的代码装配起
来了。
甚至可以说，目前写的测试没多大用处，因为它们只是验证是否正确地配置了
Express
。
这次同样我也没法提供简单的答案。究竟要写多少测试？归根结底，你正在构建的应用类
型、你的经验层次，以及你团队的规模和配置，对此都会有很大的影响。我的建议是，与
其
不够
，还不如
多写
一点儿，这样随着经验的增长，就会知道多少才是“刚刚好”。
熵功能测试
熵
功能（带随机性的功能）测试有它自己的难点。我们可以为幸运饼的生成器再增加
一个测试，测试它的确返回了一个
随机的
幸运饼。可是如何知道某个东西是随机的
呢？一个办法是获取大量的幸运饼（响应），比如说
1000
个，然后衡量这些响应的分
布。如果这个生成器函数大体是随机的，那就说明没有哪个响应特别突出。这个办法
的不足之处在于它不是确定的。有可能（虽然实际不太可能）取到某个幸运饼的次数
是取到任何其他幸运饼次数的
10
倍，如果是这样，测试就会失败（取决于对“随机”
应该达到的样本容量阈值），然而这或许并不真的就说明所测试的系统失败了，这只是
熵系统测试的一种正常结果。在幸运饼生成器的例子中，生成
50
个幸运饼并期望其中
至少有
3
种不同的饼，可以认为是合理的。反过来说，如果我们是为某科学仿真或安
全组件开发一个随机源，就很可能希望进行更细致的测试。所以，测试熵功能是很困
难的，需要更多的思考。
5.8
集成测试
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.