move maybeGen to Common

tests/Tests/Arbitrary/Common.hs

@@ -1,5 +1,6 @@
 module Tests.Arbitrary.Common where
 
+import           Control.Applicative ((<$>))
 import           Data.Char
 import qualified Data.Text as Text
 import           Test.QuickCheck
@@ -12,6 +13,11 @@ shrinkTextMaybe :: Maybe Text.Text -> [Maybe Text.Text]
 shrinkTextMaybe mbtxt = filter (\mb -> mb /= Just (Text.empty)) $ shrink mbtxt
 
 genText1 :: Gen Text.Text
-genText1 = Text.pack `fmap` string1
+genText1 = Text.pack <$> string1
   where
     string1 = listOf1 arbitrary `suchThat` (not . all isSpace)
+
+maybeGen :: Gen a -> Gen (Maybe a)
+maybeGen g = oneof [ return Nothing
+                   , Just <$> g
+                   ]

tests/Tests/Arbitrary/Xmpp.hs

@@ -26,9 +26,7 @@ instance Arbitrary Jid where
         tryJid = jidFromTexts <$> maybeGen (genString nodeprepProfile)
                               <*> genString (SP.namePrepProfile False)
                               <*> maybeGen (genString resourceprepProfile)
-        maybeGen g = oneof [ return Nothing
+
-                           , Just <$> g
-                           ]
         genString profile = Text.pack . take 1024 <$> listOf1 genChar
           where
             genChar = arbitrary `suchThat` (not . isProhibited)
@@ -55,14 +53,12 @@ instance Arbitrary LangTag where
     shrink (LangTag lt lts) = [LangTag lt' lts | lt' <- shrinkText1 lt] ++
                               [LangTag lt lts' | lts' <- filter (not . Text.null)
                                                          <$> shrink lts]
-
+`
 
 instance Arbitrary StanzaError where
     arbitrary = StanzaError <$> arbitrary
                             <*> arbitrary
-                            <*> oneof [ return Nothing
+                            <*> maybeGen ((,) <$> arbitrary <*> genText1)
-                                      , Just <$> ((,) <$> arbitrary <*> genText1)
-                                      ]
                             <*> arbitrary
 
 -- Auto-derive trivial instances