Как правильно отделить пакет библиотеки от тестов?

module Data.MySet
    ( MySet
    , empty
    , singleton
    , insert
    , member
    , len
    , fromList
    , toList
    ) where
 
data MySet a = Nil
             | Node (MySet a) (MySet a) a
               deriving (Eq)
 
toList :: MySet a -> [a]
toList Nil = []
toList (Node l r a) = a : toList l ++ toList r
 
fromList :: Ord a => [a] -> MySet a
fromList = foldl (flip insert) Nil
 
instance Show a => Show (MySet a) where
    show = ("fromList " ++) . show . toList
 
empty :: MySet a
empty = Nil
 
singleton :: a -> MySet a
singleton = Node Nil Nil
 
insert :: Ord a => a -> MySet a -> MySet a
insert a Nil       = singleton a
insert a n@(Node l r a')
       | a < a'    = Node (insert a l) r a'
       | a > a'    = Node l (insert a r) a'
       | otherwise = n
 
member :: Ord a => a -> MySet a -> Bool
member _ Nil       = False
member a (Node l r a')
       | a < a'    = member a l
       | a > a'    = member a r
       | otherwise = True
 
len :: MySet a -> Int
len Nil          = 0
len (Node l r _) = 1 + len l + len r

module Data.MySet.Tests (tests) where
 
import Test.Framework (Test)
import Test.Framework.Providers.HUnit
import Test.HUnit hiding (Test)
 
import Data.MySet
 
import Control.Applicative
 
testAddDuplicate :: Test
testAddDuplicate =
    testCase "add duplicate to set" $ do
      assertBool "set mustn't contain duplicates" $ len set1 == len set2
          where set1 = fromList [1,2,3]
                set2 = insert 2 set1
 
tests :: [Test]
tests = [testAddDuplicate]

module Main where
 
import Test.Framework (defaultMain, testGroup)
import qualified Data.MySet.Tests
 
main :: IO ()
main = defaultMain tests
    where
      tests = [ testGroup "Data.MySet.Tests" Data.MySet.Tests.tests ]