testing - Organizing Haskell Tests

Question

So I'm trying to follow the suggested structure of a Haskell project, and I'm having a couple problems organizing my tests.

For simplicity, let's start with:

src/Clue/Cards.hs # defines Clue.Cards module
testsuite/tests/Clue/Cards.hs # tests Clue.Cards module

For one, I'm not sure what to name the module in testsuite/tests/Clue/Cards.hs that contains the test code, and for another, I'm no sure how to compile my test code so that I can link to my source:

% ghc -c testsuite/tests/Clue/Cards.hs -L src
testsuite/tests/Clue/Cards.hs:5:0:
    Failed to load interface for `Clue.Cards':
      Use -v to see a list of the files searched for.

Answer 1

I use myself the approach taken by Snap Framework for their test-suites, which basically boils down to:

1. Use a test-framework such as haskell-test-framework or HTF

2. Name the modules containing tests by appending .Tests to the module-name containing the IUT, e.g.:

   module Clue.Cards where ... -- module containing IUT
   
   module Clue.Cards.Tests where ... -- module containing tests for IUT
   

3. By using separate namespaces, you can put your tests in a separate source-folder tests/, you can then use a separate Cabal build-target (see also cabal test-build-target support in recent Cabal versions) for the test-suite which includes the additional source folder in its hs-source-dirs setting, e.g.:

   Executable clue
     hs-source-dirs: src
     ...
   
   Executable clue-testsuite
     hs-source-dirs: src tests
     ...
   

   This works, since there's no namespace collision between the modules in your IUT and the test-suite anymore.