gistfile1.hs

import Test.HUnit
import Control.Applicative

data Piece = Cross | Circle deriving (Show, Eq)

isWon :: [Maybe Piece] -> Bool
isWon []           = False
isWon (x:xs)
    | x == Nothing = False
    | null xs      = True
    | x /= head xs = False
    | otherwise    = isWon xs

isWonTests = TestList [
                "test list with Nothing" ~: False ~=? (isWon [Nothing])
              , "test unequal list"      ~: False ~=?
                                             (isWon [Just Circle, Just Cross])
              , "test empty list"        ~: False ~=? (isWon [])
              , "test won list"          ~: True ~=?
                                             (isWon [Just Circle, Just Circle])
             ]

main = runTestTT isWonTests