Test node.js function for different operating systems [on hold]

I have some function that makes some stuff which differs for different operating systems. So I want to write unit test for that function which checks that my function works correctly in supported operating systems. How can I do that? How to write unit test that runs my function in different operating systems and tells me in which operating system my function does not work?

I think the test must run several virtual machines with different operating systems on it (using VirtualBox for example) and call my function there. But I don't know how to do it.

UPD Please, provide some code in your answer, cause this is the real problem for me.