Skipping files from coverage

I have a very different requirement to exclude some files from test coverage.

I have a few files which are meant to work on Linux and not on Mac OS X and based on the underline platform I either run the test or don't. I have addressed running test cases based on platform, but need to somehow exclude that particular file from test coverage as well.

Can I apply the condition for the platform to a config file where we omit files from coverage?