[commit: packages/binary] master: Increase test coverage for Binary Natural instance. (916372c)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/binary

On branch  : master
Link       : http://git.haskell.org/packages/binary.git/commitdiff/916372c846e50e84da0ce262f57c685be22f46ba

>---------------------------------------------------------------

commit 916372c846e50e84da0ce262f57c685be22f46ba
Author: Lennart Kolmodin <kolmodin at google.com>
Date:   Sun May 31 16:41:04 2015 +0200

    Increase test coverage for Binary Natural instance.
    
    The arbitrarySizedNatural creates too small Naturals so we didn't test
    all code paths. Use a custom generator to get bigger numbers.


>---------------------------------------------------------------

916372c846e50e84da0ce262f57c685be22f46ba
 tests/QC.hs | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/tests/QC.hs b/tests/QC.hs
index b0b4c8f..addf185 100644
--- a/tests/QC.hs
+++ b/tests/QC.hs
@@ -358,10 +358,20 @@ main = defaultMain tests
 ------------------------------------------------------------------------
 
 #ifdef HAS_NATURAL
--- | Until the QuickCheck library implements instance Arbitrary Natural,
--- we need this test.
 prop_test_Natural :: Property
-prop_test_Natural = forAll (arbitrarySizedNatural :: Gen Natural) test
+prop_test_Natural = forAll (gen :: Gen Natural) test
+  where
+    gen :: Gen Natural
+    gen = do
+      b <- arbitrary
+      if b
+        then do
+          x <- arbitrarySizedNatural :: Gen Natural
+          -- arbitrarySizedNatural generates numbers smaller than
+          -- (maxBound :: Word64), so let's make them bigger to better test
+          -- the Binary instance.
+          return (x + fromIntegral (maxBound :: Word64))
+        else arbitrarySizedNatural
 #endif
 
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