So I use mocha and eslint, how do I configure those tools to allow test files in the same directories as the source? The sticking point I found is enabling dif

So I use mocha and eslint, how do I configure those tools to allow test files in the same directories as the source? The sticking point I found is enabling different lint rule for test and source in a way that doesn't require linting twice and that is automatically understood by my editor (vim + syntastic)