To limit the possible damage done by changes, unit tests and integration tests are mandatory, otherwise the entire functionality of the system needs to be hand-tested after each change.

为了限制变更可能造成的破坏，单元测试和集成测试是必须的，否则就要在每次变更后手动测试整个系统的功能。

youdao

You can write functional tests that run in each browser, and then implement some form of continuous integration system that runs the functional tests upon each check-in of the source code.

您可以编写在每个浏览器中运行的功能测试，然后实现一个根据源代码的每次签入运行功能测试的持续集成系统。

youdao

On top of those sit integration and end-to-end system tests, which verify that the units work in concert.

在这之上是集成的、端到端的系统测试，它验证各单元是否可以协调工作。

youdao