Haskell is well known for its advanced type system and the safety and certainty it brings to your code. I’ve read the phrase “if it compiles, it works” from time to time. It is true that the type system catches a lot of mistakes early on and prevents you from creating certain types of bugs. However, it still pays of to write code tests in Haskell. That’s why there are a couple of great testing libraries like QuickCheck and HUnit.
Since both have a different approach to testing (HUnit uses the more traditional approach of xUnit architecture whereas QuickCheck does a type of testing often called property testing), I would like to use both. After some googling I found the test-framework library that enables you to do this easily. Another option is tasty, I didn’t try this but it should work as well.
Trying to set up the tests took me a little longer than I would have liked, so I’m documenting what I found here hoping that it will be of help to someone (maybe it will help myself in a few months).
The first thing you should do is add the following to your .cabal file
test-suite mytests
type: exitcode-stdio-1.0
main-is:
Test.hs
hs-source-dirs:
test, src
build-depends:This is assuming that your tests are located in the test directory, the source is located in the src directory and the main function calling your tests is inside Test.hs.
The build-depends should contain all the same dependencies as the library or executable you are testing, as well as the test libraries: HUnit, QuickCheck, test-framework, test-framework-hunit, test-framework-quickcheck2.
To correctly set up your environment do
cabal install --dependencies-only --enable-tests -j
cabal configure --enable-tests
cabal install -jNow you’re finally ready to run your tests by executing
cabal test