Guidance on the location of EUnit tests for a module?

[stevenproctor]

When digging in and trying to get an understanding about using EUnit for testing Erlang modules, I have seen examples that use three different locations for where people put there tests:

• In the same file using the testing macro
• In a different file in the same directory as the source file they are testing
• In a different file in a test(s) directory located at the same directory level as src

I don't know if it would be worth it for this book to touch on all of the different ways that they get structured and their pros/cons, or even just to vouch for one and help to standardize a structure.