-- File created: 2009-01-30 15:01:02

module Tests.Instances (tests) where

import Data.Monoid (mempty, mappend)
import Test.Framework
import Test.Framework.Providers.QuickCheck
import Test.QuickCheck ((==>))

import System.FilePath.Glob.Base (tryCompileWith)
import System.FilePath.Glob.Match
import System.FilePath.Glob.Simplify

import Tests.Base

tests = testGroup "Instances"
   [ testProperty "monoid-law-1" prop_monoidLaw1
   , testProperty "monoid-law-2" prop_monoidLaw2
   , testProperty "monoid-law-3" prop_monoidLaw3
   , testProperty "monoid-4"     prop_monoid4
   ]

-- The monoid laws: associativity...
prop_monoidLaw1 opt x y z =
   let o       = unCOpts opt
       es      = map (tryCompileWith o . unPS) [x,y,z]
       [a,b,c] = map fromRight es
    in all isRight es && mappend a (mappend b c) == mappend (mappend a b) c

-- ... left identity ...
prop_monoidLaw2 opt x =
   let o = unCOpts opt
       e = tryCompileWith o (unPS x)
       a = fromRight e
    in isRight e && mappend mempty a == a

-- ... and right identity.
prop_monoidLaw3 opt x =
   let o = unCOpts opt
       e = tryCompileWith o (unPS x)
       a = fromRight e
    in isRight e && mappend a mempty == a

-- mappending two Patterns should be equivalent to appending the original
-- strings they came from and compiling that
--
-- (notice: relies on the fact that our Arbitrary instance doesn't generate
-- unclosed [] or <>; we only check for **/)
prop_monoid4 opt x y =
   let o     = unCOpts opt
       es    = map (tryCompileWith o . unPS) [x,y]
       [a,b] = map fromRight es
       cat1  = mappend a b
       cat2  = tryCompileWith o (unPS x ++ unPS y)
       last2 = take 2 . reverse . unPS $ x
       head2 = take 2 . unPS $ y
    in     (last2 /= "**" && take 1 head2 /= "/")
        && (take 1 last2 /= "*" && take 2 head2 /= "*/")
       ==> all isRight es && isRight cat2 && cat1 == fromRight cat2