Set stdout/err encoding to UTF-8 on Windows

See:
- hedgehogqa#110
- hedgehogqa#178

hedgehog/src/Hedgehog/Internal/Report.hs

@@ -1,4 +1,5 @@
 {-# OPTIONS_HADDOCK not-home #-}
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveTraversable #-}
@@ -63,6 +64,9 @@ import           System.Console.ANSI (ColorIntensity(..), Color(..))
 import           System.Console.ANSI (ConsoleLayer(..), ConsoleIntensity(..))
 import           System.Console.ANSI (SGR(..), setSGRCode)
 import           System.Directory (makeRelativeToCurrentDirectory)
+#if mingw32_HOST_OS
+import           System.IO (hSetEncoding, stdout, stderr, utf8)
+#endif
 
 import           Text.PrettyPrint.Annotated.WL (Doc, (<+>))
 import qualified Text.PrettyPrint.Annotated.WL as WL
@@ -781,7 +785,7 @@ ppSummary summary =
         ]
 
 renderDoc :: MonadIO m => Maybe UseColor -> Doc Markup -> m String
-renderDoc mcolor doc = do
+renderDoc mcolor doc = liftIO $ do
   let
     dull =
       SetColor Foreground Dull
@@ -885,6 +889,10 @@ renderDoc mcolor doc = do
         DisableColor ->
           WL.display
 
+#if mingw32_HOST_OS
+  hSetEncoding stdout utf8
+  hSetEncoding stderr utf8
+#endif
   pure .
     display .
     WL.renderSmart 100 $

hedgehog/src/Hedgehog/Internal/Runner.hs

@@ -1,5 +1,6 @@
 {-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE DoAndIfThenElse #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
@@ -45,6 +46,9 @@ import           Hedgehog.Range (Size)
 
 import           Language.Haskell.TH.Lift (deriveLift)
 
+#if mingw32_HOST_OS
+import           System.IO (hSetEncoding, stdout, stderr, utf8)
+#endif
 
 -- | Configuration for a property test run.
 --
@@ -265,6 +269,10 @@ checkGroup config (Group group props) =
     -- our tests will saturate all the capabilities they're given.
     updateNumCapabilities (n + 2)
 
+#if mingw32_HOST_OS
+    hSetEncoding stdout utf8
+    hSetEncoding stderr utf8
+#endif
     putStrLn $ "━━━ " ++ unGroupName group ++ " ━━━"
 
     verbosity <- resolveVerbosity (runnerVerbosity config)