How to test github branches at the same time?

Question

git

Good afternoon, I'm trying to deal with github. I read about branches and realized that this is a very useful feature for developing different modules.
The question is, let's say we are developing a site, the master branch is on our main web server, and for example coder A is working on the implementation of some function, how can he test the performance of this function so as not to disrupt the work on the main web server?
The only thing that comes to mind is a separate web server for this. But maybe there are already solutions? Some kind of service, knowledgeable advise, please.

Answer 1

Continuous Integration ( https://ru.wikipedia.org/wiki/%D0%9D%D0%B5%D0%BF%D...