{-# LANGUAGE TemplateHaskell, FlexibleInstances, TypeSynonymInstances #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

{-| Unittests for ganeti-htools.

-}

{-

Copyright (C) 2009, 2010, 2011, 2012, 2013 Google Inc.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-}

module Test.Ganeti.BasicTypes (testBasicTypes) where

import Test.QuickCheck hiding (Result)
import Test.QuickCheck.Function

import Control.Applicative
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
  [ printTestCase "return a >>= k == k a" ((return a >>= k) ==? k a)
  , printTestCase "m >>= return == m" ((m >>= return) ==? m)
  , printTestCase "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) =
  printTestCase "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...
  printTestCase "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
  ]