Tweak QC instances

The shrink support was not useful.
Also reduce the data size to make the tests run a bit quicker.

Author: dcoutts

test/Test.hs

@@ -77,6 +77,7 @@ prop_gziporzlib2 :: CompressParams
                  -> DecompressParams
                  -> Property
 prop_gziporzlib2 cp dp =
+   decompressWindowBits dp >= compressWindowBits cp &&
    decompressBufferSize dp > 0 && compressBufferSize cp > 0 ==>
    liftM2 (==) (decompress gzipOrZlibFormat dp . compress gzipFormat cp) id
 

test/Test/Codec/Compression/Zlib/Internal.hs

@@ -9,7 +9,7 @@ import Codec.Compression.Zlib.Internal
 import Test.Codec.Compression.Zlib.Stream ()
 import Test.QuickCheck
 
-import Control.Monad (ap, msum)
+import Control.Monad (ap)
 
 
 deriving instance Show CompressParams
@@ -20,24 +20,6 @@ instance Arbitrary CompressParams where
                                     `ap` arbitrary `ap` arbitraryBufferSize
                                     `ap` return Nothing
 
-  -- this definition (and the equivalent in DecompressParams below) could be
-  -- made nicer using Data.Accessor, but it's probably not worth the
-  -- dependency
-  shrink cp = msum [
-                return (\lv -> cp { compressLevel = lv }) `ap`
-                                         shrink (compressLevel cp),
-                return (\mt -> cp { compressMethod = mt }) `ap`
-                                         shrink (compressMethod cp),
-                return (\wb -> cp { compressWindowBits = wb }) `ap`
-                                         shrink (compressWindowBits cp),
-                return (\ml -> cp { compressMemoryLevel = ml }) `ap`
-                                         shrink (compressMemoryLevel cp),
-                return (\st -> cp { compressStrategy = st }) `ap`
-                                         shrink (compressStrategy cp),
-                return (\bs -> cp { compressBufferSize = bs }) `ap`
-                                         shrink (compressBufferSize cp)
-              ]
-
 arbitraryBufferSize :: Gen Int
 arbitraryBufferSize = frequency $ [(10, return n) | n <- [1..1024]] ++
                                   [(20, return n) | n <- [1025..8192]] ++
@@ -48,10 +30,7 @@ arbitraryBufferSize = frequency $ [(10, return n) | n <- [1..1024]] ++
 deriving instance Show DecompressParams
 
 instance Arbitrary DecompressParams where
-  arbitrary = return DecompressParams `ap` arbitrary `ap` arbitraryBufferSize `ap` return Nothing
-  shrink dp = msum [
-                return (\wb -> dp { decompressWindowBits = wb }) `ap`
-                      shrink (decompressWindowBits dp),
-                return (\bs -> dp { decompressBufferSize = bs }) `ap`
-                      shrink (decompressBufferSize dp)
-              ]
+  arbitrary = return DecompressParams `ap` arbitrary
+                                      `ap` arbitraryBufferSize
+                                      `ap` return Nothing
+

test/Test/Codec/Compression/Zlib/Stream.hs

@@ -27,8 +27,6 @@ instance Arbitrary CompressionLevel where
 deriving instance Ord WindowBits
 instance Arbitrary WindowBits where
   arbitrary = elements $ defaultWindowBits:map windowBits [8..15]
-  shrink DefaultWindowBits = []
-  shrink (WindowBits n) = defaultWindowBits:map windowBits [n+1..15]
 
 
 instance Arbitrary MemoryLevel where

test/Utils.hs

@@ -10,7 +10,7 @@ import Test.QuickCheck
 -- QuickCheck Utils
 
 maxStrSize :: Double
-maxStrSize = 5000
+maxStrSize = 500
 
 -- convert a QC size parameter into one for generating long lists,
 -- growing inverse exponentially up to maxStrSize