content: {-# LANGUAGE TemplateHaskell, FlexibleInstances, TypeSynonymInstances #-}
  {-# OPTIONS_GHC -fno-warn-orphans #-}
  
  {-| Unittests for ganeti-htools.
  
  -}
  
  {-
  
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  module Test.Ganeti.BasicTypes (testBasicTypes) where
  
  import Test.QuickCheck hiding (Result)
  import Test.QuickCheck.Function
  
  import Control.Monad
  
  import Test.Ganeti.TestHelper
  import Test.Ganeti.TestCommon
  
  import Ganeti.BasicTypes
  
  -- Since we actually want to test these, don't tell us not to use them :)
  
  {-# ANN module "HLint: ignore Functor law" #-}
  {-# ANN module "HLint: ignore Monad law, left identity" #-}
  {-# ANN module "HLint: ignore Monad law, right identity" #-}
  {-# ANN module "HLint: ignore Use >=>" #-}
  {-# ANN module "HLint: ignore Use ." #-}
  
  -- * Arbitrary instances
  
  instance (Arbitrary a) => Arbitrary (Result a) where
    arbitrary = oneof [ Bad <$> arbitrary
                      , Ok  <$> arbitrary
                      ]
  
  -- * Test cases
  
  -- | Tests the functor identity law:
  --
  -- > fmap id == id
  prop_functor_id :: Result Int -> Property
  prop_functor_id ri =
    fmap id ri ==? ri
  
  -- | Tests the functor composition law:
  --
  -- > fmap (f . g)  ==  fmap f . fmap g
  prop_functor_composition :: Result Int
                           -> Fun Int Int -> Fun Int Int -> Property
  prop_functor_composition ri (Fun _ f) (Fun _ g) =
    fmap (f . g) ri ==? (fmap f . fmap g) ri
  
  -- | Tests the applicative identity law:
  --
  -- > pure id <*> v = v
  prop_applicative_identity :: Result Int -> Property
  prop_applicative_identity v =
    pure id <*> v ==? v
  
  -- | Tests the applicative composition law:
  --
  -- > pure (.) <*> u <*> v <*> w = u <*> (v <*> w)
  prop_applicative_composition :: Result (Fun Int Int)
                               -> Result (Fun Int Int)
                               -> Result Int
                               -> Property
  prop_applicative_composition u v w =
    let u' = fmap apply u
        v' = fmap apply v
    in pure (.) <*> u' <*> v' <*> w ==? u' <*> (v' <*> w)
  
  -- | Tests the applicative homomorphism law:
  --
  -- > pure f <*> pure x = pure (f x)
  prop_applicative_homomorphism :: Fun Int Int -> Int -> Property
  prop_applicative_homomorphism (Fun _ f) x =
    ((pure f <*> pure x)::Result Int) ==? pure (f x)
  
  -- | Tests the applicative interchange law:
  --
  -- > u <*> pure y = pure ($ y) <*> u
  prop_applicative_interchange :: Result (Fun Int Int)
                               -> Int -> Property
  prop_applicative_interchange f y =
    let u = fmap apply f -- need to extract the actual function from Fun
    in u <*> pure y ==? pure ($ y) <*> u
  
  -- | Tests the applicative\/functor correspondence:
  --
  -- > fmap f x = pure f <*> x
  prop_applicative_functor :: Fun Int Int -> Result Int -> Property
  prop_applicative_functor (Fun _ f) x =
    fmap f x ==? pure f <*> x
  
  -- | Tests the applicative\/monad correspondence:
  --
  -- > pure = return
  --
  -- > (<*>) = ap
  prop_applicative_monad :: Int -> Result (Fun Int Int) -> Property
  prop_applicative_monad v f =
    let v' = pure v :: Result Int
        f' = fmap apply f -- need to extract the actual function from Fun
    in v' ==? return v .&&. (f' <*> v') ==? f' `ap` v'
  
  -- | Tests the monad laws:
  --
  -- > return a >>= k == k a
  --
  -- > m >>= return == m
  --
  -- > m >>= (\x -> k x >>= h) == (m >>= k) >>= h
  prop_monad_laws :: Int -> Result Int
                  -> Fun Int (Result Int)
                  -> Fun Int (Result Int)
                  -> Property
  prop_monad_laws a m (Fun _ k) (Fun _ h) =
    conjoin
    [ counterexample "return a >>= k == k a" ((return a >>= k) ==? k a)
    , counterexample "m >>= return == m" ((m >>= return) ==? m)
    , counterexample "m >>= (\\x -> k x >>= h) == (m >>= k) >>= h)"
      ((m >>= (\x -> k x >>= h)) ==? ((m >>= k) >>= h))
    ]
  
  -- | Tests the monad plus laws:
  --
  -- > mzero >>= f = mzero
  --
  -- > v >> mzero = mzero
  prop_monadplus_mzero :: Result Int -> Fun Int (Result Int) -> Property
  prop_monadplus_mzero v (Fun _ f) =
    counterexample "mzero >>= f = mzero" ((mzero >>= f) ==? mzero) .&&.
    -- FIXME: since we have "many" mzeros, we can't test for equality,
    -- just that we got back a 'Bad' value; I'm not sure if this means
    -- our MonadPlus instance is not sound or not...
    counterexample "v >> mzero = mzero" (isBad (v >> mzero))
  
  testSuite "BasicTypes"
    [ 'prop_functor_id
    , 'prop_functor_composition
    , 'prop_applicative_identity
    , 'prop_applicative_composition
    , 'prop_applicative_homomorphism
    , 'prop_applicative_interchange
    , 'prop_applicative_functor
    , 'prop_applicative_monad
    , 'prop_monad_laws
    , 'prop_monadplus_mzero
    ]
  