[Haskell-beginners] HUnit - testing for failed pattern match
xavier-list at rhnh.net
Sat Feb 26 02:47:38 CET 2011
On 26/02/11 12:36 PM, Daniel Fischer wrote:
> On Saturday 26 February 2011 02:08:48, Xavier Shay wrote:
>> Excellent. I had to update the code to use the new Control.Exception
>> (rather than Control.OldException), and ended up with:
>> import Control.Exception
>> TestCase $ do
>> handle (\(_ :: ErrorCall) -> return ()) $ do
>> evaluate ( myFunc 3 [False, False, True] )
>> assertFailure "must raise an error on invalid state"
>> The only issue is that I now require the -XScopedTypeVariables flag,
>> otherwise it fails to compile with:
>> Illegal signature in pattern: ErrorCall
>> Use -XScopedTypeVariables to permit it
>> I am not sure whether this is an acceptable solution or not.
> ScopedTypeVariables is harmless, so it is accetable. But if you prefer, you
> can avoid it with a top-level handler
> ignoreErrorCalls :: ErrorCall -> IO ()
> ignoreErrorCalls _ = return ()
> TestCase $
> ignoreErrorCalls $ do
> evaluate ( myFunc 3 [False, False, True] )
> assertFailure "must raise an error on invalid state"
> or an explicit pattern in the handler,
> TestCase $
> handle (\(ErrorCall _) -> return ()) $ do
> evaluate ...
> I think (code untested).
tested the latter - totally works
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