How to achieve PHPUnitTest with assertions on GIT?

I have a GITWrapper which maintains a GIT directory. For a couple of tests I need those things:

• A directory with GIT


• One initial commit containing no file


• One commit containing a couple of new files


• One commit containing some changes to the files

And this for a couple of tests.

• How would you achieve this in GIT?


• Where would those files be placed?


• And how to rollback all these changes?

I would love to see a common way to solve this. vfsStream might be a solution but I am not very sure what is the right solution for these kinds of pre-conditions.