New RECREATE_GOLDEN_FILES which will causes golden tests to always cr…

…eate golden files replacing any existing golden files

src/Hedgehog/Extras/Test/Golden.hs

@@ -49,10 +49,17 @@ createFiles = IO.unsafePerformIO $ do
   value <- IO.lookupEnv "CREATE_GOLDEN_FILES"
   return $ value == Just "1"
 
+-- | Whether the test should create the golden files if the file does ont exist.
+recreateFiles :: Bool
+recreateFiles = IO.unsafePerformIO $ do
+  value <- IO.lookupEnv "RECREATE_GOLDEN_FILES"
+  return $ value == Just "1"
+
 -- | Diff contents against the golden file.  If CREATE_GOLDEN_FILES environment is
--- set to "1", then should the gold file not exist it would be created.  If
--- GOLDEN_FILE_LOG_FILE is set to a filename, then the golden file path will be
--- logged to the specified file.
+-- set to "1", then should the golden file not exist it would be created.  If
+-- RECREATE_GOLDEN_FILES is set to "1", then should the golden file exist it would
+-- be recreated. If GOLDEN_FILE_LOG_FILE is set to a filename, then the golden file
+-- path will be logged to the specified file.
 --
 -- Set the environment variable when you intend to generate or re-generate the golden
 -- file for example when running the test for the first time or if the golden file
@@ -75,8 +82,10 @@ diffVsGoldenFile actualContent referenceFile = GHC.withFrozenCallStack $ do
 
   fileExists <- liftIO $ IO.doesFileExist referenceFile
 
-  if fileExists
+  if fileExists && not recreateFiles
     then do
+      -- RECREATE_GOLDEN_FILES is not set so we compare the actual content against
+      -- the golden file.
       referenceLines <- List.lines <$> H.readFile referenceFile
       let difference = getGroupedDiff actualLines referenceLines
       case difference of
@@ -85,14 +94,15 @@ diffVsGoldenFile actualContent referenceFile = GHC.withFrozenCallStack $ do
         _        -> do
           H.note_ $ "Golden test failed against golden file: " <> referenceFile
           failMessage callStack $ ppDiff difference
-    else if createFiles
+    else if createFiles || recreateFiles
       then do
-        -- CREATE_GOLDEN_FILES is set, so we create any golden files that don't
-        -- already exist.
+        -- Either CREATE_GOLDEN_FILES or RECREATE_GOLDEN_FILES is set, so we create any
+        -- golden files that don't already exist.
         H.note_ $ "Creating golden file " <> referenceFile
         H.createDirectoryIfMissing_ (takeDirectory referenceFile)
         H.writeFile referenceFile actualContent
       else do
+        -- Neither CREATE_GOLDEN_FILES nor RECREATE_GOLDEN_FILES is set, so we fail
         H.note_ $ mconcat
           [ "Golden file " <> referenceFile
           , " does not exist.  To create, run with CREATE_GOLDEN_FILES=1"