[Haskell-beginners] HUnit - testing for failed pattern match
Edward Z. Yang
ezyang at MIT.EDU
Tue Feb 22 15:31:57 CET 2011
A partial function will emit an exception, which must be caught from
IO. I'm sure HUnit has an appropriate mechanism for handling this,
but I strongly suggest you redesign your function to be total: instead
of omitting pattern matches, change it to use Maybe and return Nothing
in the 'otherwise' case.
Excerpts from Xavier Shay's message of Tue Feb 22 05:59:12 -0500 2011:
> Given the following contrived function:
> giveMeThree x
> | x == 3 = True
> How do I test with HUnit that 2 is invalid input?
> giveMeThreeTests =
> [ "Likes 3" ~: True ~=? giveMeThree 3
> , "Dislikes 2" ~: ..... -- what?
> I couldn't find anything mentioned in the HUnit user guide. References
> to appropriate documentation appreciated.
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