How to properly connect Mocha tests to your project?

Question

JavaScript

Can you please tell me how to properly connect tests to your project ?? The fact is that all my code is divided into several files. The code of a single file is enclosed in a self-calling function. The necessary properties and methods are externally exported through the window object. I tried to access them in the test file via window, require + window. As a result all the same tests do not see my code. How to connect tests correctly?
PS A test written for a global function finds it and runs. And it does not see the local areas of modules (