Haskell unit testing

Question

I\'m new to haskell and working on unit testing, however I find the ecosystem to be very confusing. I\'m confused as to the relationship between HTF and HUnit.

In som

Answer 1

You've had answers to most of your questions, but you also asked about HTF, and how that works.

HTF is a framework that is designed for both unit testing -- it is backwards compatible with HUnit (it integrates and wraps it to provide extra functions) -- and property-based testing -- it integrates with quickcheck. It uses a preprocessor to locate tests so that you don't have to manually build a list. The preprocessor is added to your test source files using a pragma:

{-# OPTIONS_GHC -F -pgmF htfpp #-}

(alternatively, I guess you could add the same options to your ghc-options property in your cabal file, but I've never tried this so don't know if it is useful or not).

The preprocessor scans your module for top-level functions named test_xxxx or prop_xxxx and adds them to a list of tests for the module. You can either use this list directly by putting a main function in the module and running them (main = htfMain htf_thisModuleTests) or export them from the module, and have a main test program for multiple modules, which imports the modules with tests and runs all of them:

import {-@ HTF_TESTS @-} ModuleA
import {-@ HTF_TESTS @-} ModuleB
main :: IO ()
main = htfMain htf_importedTests

This program can be integrated with cabal using the technique described by @jozefg, or loaded into ghci and run interactively (although not on Windows - see https://github.com/skogsbaer/HTF/issues/60 for details).

Tasty is another alternative that provides a way of integrating different kinds of tests. It doesn't have a preprocessor like HTF, but has a module that performs similar functions using Template Haskell. Like HTF, it also relies on naming convention to identify your tests (in this case, case_xxxx rather than test_xxxx). In addition to HUnit and QuickCheck tests, it also has modules for handling a number of other test types.