Pitest

传统的测试方法通常聚焦于评估我们的生产代码是不是在做该做的事情。然而，我们也可能在测试代码中犯错，比如引入了不完整或者无用的断言，导致盲目的自信。这就是变异测试的由来；它会评估测试自身的质量，发现很难意识到的临界情况。我们的团队使用 Pitest 已经有一阵子了，现在推荐在 Java 项目中使用它，用于衡量测试套件的健康程度。简而言之，变异测试会给生产代码引入一点变化，然后再次执行相同的测试；如果测试仍然是绿色的，意味着测试不够好仍然需要改进。如果你在使用 Java 以外的语言，那 Stryker 是个好的选择。

Pitest is a test coverage analysis tool for Java that uses a mutation-testing technique. Traditional test coverage analysis tends to measure the number of lines that are executed by your tests. It is therefore only able to identify code that is definitely not tested. Mutation testing, on the other hand, tries to test the quality of those lines that are executed by your test code and yet might contain general errors. Several problems can be spotted this way, helping the team to measure and grow a healthy test suite. Most of such tools tend to be slow and difficult to use, but Pitest has proven to have better performance, is easy to set up, and is actively supported.