QuickCheck catch-22

Question

I'm working on a Haskell project and I started out by organizing it like this:

• blah.hs holds the majority of the code
• blah_main.hs has the main program
• and blah_test.hs has the test cases.

The problem with this is that restricting the functions exported by blah.hs means restricting the functions that can be tested from blah_test.hs. Is there a good way around this issue? Because I'd really like to write test code for some of the "internal" functions that aren't being exported by blah.hs.

Thanks, Lee

Answer 1

Move internal functions from the Blah.* modules to Blah.Internal.* . You can hide internal modules from the users of your library by listing them in the other-modules field in the blah.cabal file (instead of exposed-modules, where you list all modules visible to the users). Look at Hakyll's .cabal file for an example.

Answer 2

I agree with Mikhail over all, but in some circumstances it's not really possible to make such a split. In those cases, I would recommend using the CPP (C Pre-Processor) extension, along the lines of:

module Blah
    ( public
#if TEST
    , private
#endif
    ) where