TDD add exercise (no errors yet)

TDD.hs

module TDD (add) where

import qualified Data.Text as T

data ArgumentError = ArgumentError deriving (Show)

add :: String -> Integer
add s = sum $ map toI $ T.split (\d -> d == ',' || d == '\n') (T.pack s)

toI :: T.Text -> Integer
toI s = case reads (T.unpack s) of
	((n, _) : _) -> n
	_            -> 0

Test.hs

module Main (main) where

import Control.Applicative
import Test.Framework (defaultMain, testGroup, Test)
import Test.Framework.Providers.HUnit
import Test.Framework.Providers.QuickCheck2
import Test.QuickCheck
-- import Test.QuickCheck.Instances ()
import Test.HUnit hiding (Test)
import Data.List (intercalate)

import qualified TDD

testDecode1 :: Assertion
testDecode1 = assertEqual "for 1" 1 (TDD.add "1")

propIntegerDecodeLoop :: Integer -> Bool
propIntegerDecodeLoop num = TDD.add (show num) == num

testDecodeEmpty :: Assertion
testDecodeEmpty = assertEqual "for empty" 0 (TDD.add "")

propTwoShouldDecode :: Integer -> Integer -> Bool
propTwoShouldDecode x y = TDD.add (show x ++ "," ++ show y) == x + y

propSomeShouldDecode :: [Integer] -> Bool
propSomeShouldDecode xs = TDD.add (intercalate "," (map show xs)) == sum xs

newtype Delimiter = Delimiter String deriving (Show)

instance Arbitrary Delimiter where
	arbitrary = Delimiter <$> elements [",", "\n"]

propSomeShouldDecodeDelim :: [Integer] -> Delimiter ->  Bool
propSomeShouldDecodeDelim xs (Delimiter d) = TDD.add (intercalate d (map show xs)) == sum xs

tests :: [Test]
tests =
	[
		testGroup "One number" [
			testCase "\"1\" returns 1" testDecode1,
			testProperty "Integer should decode" propIntegerDecodeLoop
		],
		testGroup "No number" [
			testCase "\"\" returns 0" testDecodeEmpty
		],
		testGroup "Two numbers" [
			testProperty "Two numbers should sum" propTwoShouldDecode
		],
		testGroup "Some numbers" [
			testProperty "Some numbers should sum" propSomeShouldDecode,
			testProperty "Some numbers should sum with comma or newline" propSomeShouldDecodeDelim
		]
	]

main :: IO ()
main = defaultMain tests