jest --findRelatedTests如何在后台工作? [英] How does jest --findRelatedTests work under the hood?

问题描述

查找并运行测试，这些测试涵盖了用空格分隔的源列表 作为参数传递的文件.对于预提交挂钩很有用 集成以运行最少数量的必要测试.

Find and run the tests that cover a space separated list of source files that were passed in as arguments. Useful for pre-commit hook integration to run the minimal amount of tests necessary.

这是官方文档，但是它如何工作?它是否分析项目中的所有导入，并且仅运行导入我要测试的文件的测试?我就是这样写的，但是它真的那样工作吗?

This is in official docs, but how does this work? Does it analyze all the imports in my project and only runs tests that import the file I want to test? That's how I would write it, but is it really working like that?

相关问题-查找相关测试时是否使用缓存?

Related question-does it use a cache when finding related tests?

推荐答案

在过去的几天里，我一直被同一个问题困扰.深入研究 Jest源代码，我想我对发生的事情非常了解.

I'v been stuck with the same question for the last few days. After digging through the Jest source code, I think I have a pretty good idea of what's going on.

运行--findRelatedTests path/to/src-code.js时，首先发生的事情是Jest创建了内部包jest-resolve-dependencies的实例.这是一个非常简单的类，具有两个方法:resolve和resolveInverse.

When running --findRelatedTests path/to/src-code.js, the first thing that happens is Jest creates an instance of an internal package, jest-resolve-dependencies. It's a pretty straightforward class with two methods: resolve and resolveInverse.

findRelatedTests在您提供的路径上调用resolveInverse，在我们的示例path/to/src-code.js中查找需要该文件的每个源文件和测试文件.该查找直接依赖于某些Jest配置，特别是roots和/或rootDir，以帮助解析路径.

findRelatedTests calls resolveInverse on the paths you provided, looking up every source and test file that requires your file, in our example path/to/src-code.js. This lookup relies directly on some Jest configuration, specifically roots and/or rootDir, to help resolve paths.

如果找到的文件是测试文件，则Jest运行它，非常简单.如果找到的文件是源文件，则将其命名为found-file.js，则任何导入found-file.js 的测试文件和导入其自身导入found-file.js的任何源文件的测试文件都将是.跑步.

If the found file is a test file, Jest runs it, simple enough. If the found file is a source file, call it found-file.js, then any test files that import found-file.js and the test files that import any of the source files that themselves import found-file.js will be run.

正如维护者所说，这是传递逆相关性"解析器的巧妙实现.您可以在此while循环.

It's a clever implementation of, as the maintainers put it, a resolver of "transitive inverse dependencies". You can see for yourself in this while loop.

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