diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Revision history for tasty-lua
 
+## 0.2.0 -- 2019-05-19
+
+- Renamed `testFileWith` to `testLuaFile`, and
+  `testsFromFile` to `translateResultsFromFile`.
+
+- Fixed and extended test summary: if all tests pass, a brief
+  summary about the number of passed tests is show. Furthermore,
+  some bugs (caused by a misused Foldable instance) have been
+  fixed.
+
+- Code has been split into multiple sub-modules.
+
 ## 0.1.1 -- 2019-05-17
 
 - Add new function `testFileWith`, allowing to run a file as a
diff --git a/src/Test/Tasty/Lua.hs b/src/Test/Tasty/Lua.hs
--- a/src/Test/Tasty/Lua.hs
+++ b/src/Test/Tasty/Lua.hs
@@ -1,6 +1,5 @@
-{-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 {-|
 Module      : Test.Tasty.Lua
 Copyright   : © 2019 Albert Krewinkel
@@ -15,166 +14,91 @@
   ( -- * Lua module
     pushModule
     -- * Running tests
-  , testFileWith
-  , testsFromFile
+  , testLuaFile
+  , translateResultsFromFile
     -- * Helpers
   , pathFailure
   )
 where
 
-import Control.Exception (throw, try)
-import Control.Monad (void)
-import Data.ByteString (ByteString)
-import Data.FileEmbed
+import Control.Exception (SomeException, try)
 import Data.List (intercalate)
-import Foreign.Lua (Lua, NumResults, Peekable, StackIndex)
-import qualified Data.Text as Text
-import qualified Data.Text.Encoding as Text.Encoding
-import qualified Foreign.Lua as Lua
-import qualified Test.Tasty as Tasty
-import qualified Test.Tasty.Providers as Tasty
+import Data.Semigroup (Semigroup (..))
+import Foreign.Lua (Lua)
+import Test.Tasty (TestName, TestTree)
+import Test.Tasty.Providers (IsTest (..), singleTest, testFailed, testPassed)
+import Test.Tasty.Lua.Module (pushModule)
+import Test.Tasty.Lua.Core (Outcome (..), ResultTree (..), UnnamedTree (..),
+                            runTastyFile)
+import Test.Tasty.Lua.Translate (pathFailure, translateResultsFromFile)
 
 -- | Run the given file as a single test. It is possible to use
 -- `tasty.lua` in the script. This test collects and summarizes all
 -- errors, but shows generally no information on the successful tests.
-testFileWith :: FilePath -> (forall a . Lua a -> IO a) -> Tasty.TestTree
-testFileWith fp runLua =
+testLuaFile :: (forall a . Lua a -> IO a)
+             -> TestName
+             -> FilePath
+             -> TestTree
+testLuaFile runLua name fp =
   let testAction = TestCase $ do
-        result <- runLua (runTastyFile fp)
-        case result >>= failuresMessage of
-          Left errMsg -> throw (Lua.Exception errMsg)
-          Right _     -> return ()
-  in Tasty.singleTest fp testAction
+        eitherResult <- runLua (runTastyFile fp)
+        return $ case eitherResult of
+          Left errMsg  -> FailureSummary [([name], errMsg)]
+          Right result -> summarize result
+  in singleTest name testAction
 
-newtype TestCase = TestCase (IO ())
+-- | Lua test case action
+newtype TestCase = TestCase (IO ResultSummary)
 
-instance Tasty.IsTest TestCase where
+instance IsTest TestCase where
   run _ (TestCase action) _ = do
     result <- try action
     return $ case result of
-      Left (Lua.Exception message) -> Tasty.testFailed message
-      Right ()                     -> Tasty.testPassed ""
+      Left e        -> testFailed (show (e :: SomeException))
+      Right summary -> case summary of
+        SuccessSummary n ->
+          testPassed $ "+++ Success: " ++ show n ++ " Lua tests passed"
+        FailureSummary fails ->
+          testFailed $ concatMap stringifyFailureGist fails
 
   testOptions = return []
 
--- | Run tasty.lua tests from the given file.
-testsFromFile :: FilePath -> Lua Tasty.TestTree
-testsFromFile fp = do
-  result <- runTastyFile fp
-  case result of
-    Left errMsg -> return $ pathFailure fp errMsg
-    Right tree  -> return $ Tasty.testGroup fp $ map testTree tree
-
--- | Run a tasty Lua script from a file and return either the resulting
--- test tree or the error message.
-runTastyFile :: FilePath -> Lua (Either String [Tree])
-runTastyFile fp = do
-  Lua.openlibs
-  Lua.requirehs "tasty" (void pushModule)
-  res <- Lua.dofile fp
-  if res == Lua.OK
-    then Right <$> Lua.peekList Lua.stackTop
-    else Left . toString <$> Lua.tostring' Lua.stackTop
-
--- | Generate a single error message from all failures in a test tree.
-failuresMessage :: [Tree] -> Either String ()
-failuresMessage tree =
-  case mapM collectFailureMessages tree of
-    Nothing   -> return ()
-    Just errs -> Left $ concatMap (concatMap stringifyFailureGist) errs
+summarize :: [ResultTree] -> ResultSummary
+summarize = foldr ((<>) . collectSummary) (SuccessSummary 0)
 
 -- | Failure message generated by tasty.lua
 type LuaErrorMessage = String
--- | Info about a test failure
-type FailureGist = ([Tasty.TestName], LuaErrorMessage)
+-- | Info about a single failure
+type FailureInfo = ([TestName], LuaErrorMessage)
 
+-- | Summary about a test result
+data ResultSummary
+  = SuccessSummary Int -- ^ Number of successful tests
+  | FailureSummary [FailureInfo]
+  -- ^ Failure messages, together with the test paths
+
 -- | Convert a test failure, given as the pair of the test's path and
 -- its error message, into an error string.
-stringifyFailureGist :: FailureGist -> String
+stringifyFailureGist :: FailureInfo -> String
 stringifyFailureGist (names, msg) =
   intercalate " // " names ++ ":\n" ++ msg ++ "\n\n"
 
 -- | Extract all failures from a test result tree.
-collectFailureMessages :: Tree -> Maybe [FailureGist]
-collectFailureMessages (Tree name tree) =
-  case tree of
-    SingleTest Success       -> Nothing
-    SingleTest (Failure msg) -> Just [([name], msg)]
-    TestGroup subtree        -> foldr go Nothing subtree
-      where go tree' acc = case acc of
-              Nothing   -> collectFailureMessages tree'
-              Just errs -> case collectFailureMessages tree' of
-                             Nothing -> Just errs
-                             Just x  -> Just (x ++ errs)
-
--- | Tasty Lua script
-tastyScript :: ByteString
-tastyScript = $(embedFile "tasty.lua")
-
--- | Push the Aeson module on the Lua stack.
-pushModule :: Lua NumResults
-pushModule = do
-  result <- Lua.dostring tastyScript
-  if result == Lua.OK
-    then return 1
-    else Lua.throwTopMessage
-{-# INLINABLE pushModule #-}
-
--- | Report failure of testing a path.
-pathFailure :: FilePath -> String -> Tasty.TestTree
-pathFailure fp errMsg = Tasty.singleTest fp (Failure errMsg)
-
--- | Convert internal (tasty.lua) tree format into Tasty tree.
-testTree :: Tree -> Tasty.TestTree
-testTree (Tree name tree) =
+collectSummary :: ResultTree -> ResultSummary
+collectSummary (ResultTree name tree) =
   case tree of
-    SingleTest outcome -> Tasty.singleTest name outcome
-    TestGroup results  -> Tasty.testGroup name (map testTree results)
-
-data Tree = Tree Tasty.TestName UnnamedTree
-
-instance Peekable Tree where
-  peek idx = do
-    name   <- Lua.getfield idx "name"   *> Lua.popValue
-    result <- Lua.getfield idx "result" *> Lua.popValue
-    return $ Tree name result
-
-instance Tasty.IsTest Outcome where
-  run _ tr _ = return $ case tr of
-    Success     -> Tasty.testPassed ""
-    Failure msg -> Tasty.testFailed msg
-  testOptions = return []
-
--- | Either a raw test outcome, or a nested @'Tree'@.
-data UnnamedTree
-  = SingleTest Outcome
-  | TestGroup [Tree]
-
-instance Peekable UnnamedTree where
-  peek = peekTree
-
-peekTree :: StackIndex -> Lua UnnamedTree
-peekTree idx = do
-  ty <- Lua.ltype idx
-  case ty of
-    Lua.TypeTable   -> TestGroup   <$> Lua.peekList idx
-    _               -> SingleTest  <$> Lua.peek idx
-
--- | Test outcome
-data Outcome = Success | Failure String
+    SingleTest Success       -> SuccessSummary 1
+    SingleTest (Failure msg) -> FailureSummary [([name], msg)]
+    TestGroup subtree        -> foldr go (SuccessSummary 0) subtree
+      where go r summary = collectSummary r <> addGroup name summary
 
-instance Peekable Outcome where
-  peek idx = do
-    ty <- Lua.ltype idx
-    case ty of
-      Lua.TypeString  -> Failure <$> Lua.peek idx
-      Lua.TypeBoolean -> do
-        b <- Lua.peek idx
-        return $ if b then Success else Failure "???"
-      _ -> do
-        s <- toString <$> Lua.tostring' idx
-        Lua.throwException ("not a test result: " ++ s)
+addGroup :: TestName -> ResultSummary -> ResultSummary
+addGroup name (FailureSummary fs) = FailureSummary (map addName fs)
+  where addName (names, msg) = (name : names, msg)
+addGroup _name summary = summary
 
--- | Convert UTF8-encoded @'ByteString'@ to a @'String'@.
-toString :: ByteString -> String
-toString = Text.unpack . Text.Encoding.decodeUtf8
+instance Semigroup ResultSummary where
+  (SuccessSummary n)  <> (SuccessSummary m)  = SuccessSummary (n + m)
+  (SuccessSummary _)  <> (FailureSummary fs) = FailureSummary fs
+  (FailureSummary fs) <> (SuccessSummary _)  = FailureSummary fs
+  (FailureSummary fs) <> (FailureSummary gs) = FailureSummary (fs ++ gs)
diff --git a/src/Test/Tasty/Lua/Core.hs b/src/Test/Tasty/Lua/Core.hs
new file mode 100644
--- /dev/null
+++ b/src/Test/Tasty/Lua/Core.hs
@@ -0,0 +1,94 @@
+{-# LANGUAGE LambdaCase #-}
+{-|
+Module      : Test.Tasty.Lua.Core
+Copyright   : © 2019 Albert Krewinkel
+License     : MIT
+Maintainer  : Albert Krewinkel <albert+hslua@zeitkraut.de>
+Stability   : alpha
+Portability : not portable, requires GHC or later
+
+Core types and functions for tasty Lua tests.
+-}
+module Test.Tasty.Lua.Core
+  ( runTastyFile
+  , ResultTree (..)
+  , Outcome (..)
+  , UnnamedTree (..)
+  )
+where
+
+import Control.Monad (void)
+import Data.ByteString (ByteString)
+import Foreign.Lua (Lua, Peekable, StackIndex)
+import Test.Tasty.Lua.Module (pushModule)
+import qualified Data.Text as Text
+import qualified Data.Text.Encoding as Text.Encoding
+import qualified Foreign.Lua as Lua
+import qualified Test.Tasty as Tasty
+
+-- | Run a tasty Lua script from a file and return either the resulting
+-- test tree or the error message.
+runTastyFile :: FilePath -> Lua (Either String [ResultTree])
+runTastyFile fp = do
+  Lua.openlibs
+  Lua.requirehs "tasty" (void pushModule)
+  res <- Lua.dofile fp
+  if res /= Lua.OK
+    then Left . toString <$> Lua.tostring' Lua.stackTop
+    else Lua.try (Lua.peekList Lua.stackTop) >>= \case
+           Left (Lua.Exception e) -> return (Left e)
+           Right trees            -> return (Right trees)
+
+-- | Convert UTF8-encoded @'ByteString'@ to a @'String'@.
+toString :: ByteString -> String
+toString = Text.unpack . Text.Encoding.decodeUtf8
+
+-- | Tree of test results returned by tasty Lua scripts. This is
+-- similar to tasty's @'TestTree'@, with the important difference that
+-- all tests have already been run, and all test results are known.
+data ResultTree = ResultTree Tasty.TestName UnnamedTree
+
+instance Peekable ResultTree where
+  peek = peekResultTree
+
+peekResultTree :: StackIndex -> Lua ResultTree
+peekResultTree idx = do
+  name   <- Lua.getfield idx "name"   *> Lua.popValue
+  result <- Lua.getfield idx "result" *> Lua.popValue
+  return $ ResultTree name result
+
+-- | Either a raw test outcome, or a nested @'Tree'@.
+data UnnamedTree
+  = SingleTest Outcome
+  | TestGroup [ResultTree]
+
+instance Peekable UnnamedTree where
+  peek = peekUnnamedTree
+
+-- | Unmarshal an @'UnnamedTree'@.
+peekUnnamedTree :: StackIndex -> Lua UnnamedTree
+peekUnnamedTree idx = do
+  ty <- Lua.ltype idx
+  case ty of
+    Lua.TypeTable   -> TestGroup   <$> Lua.peekList idx
+    _               -> SingleTest  <$> Lua.peek idx
+
+
+-- | Test outcome
+data Outcome = Success | Failure String
+
+instance Peekable Outcome where
+  peek = peekOutcome
+
+-- | Unmarshal a test outcome
+peekOutcome :: StackIndex -> Lua Outcome
+peekOutcome idx = do
+  ty <- Lua.ltype idx
+  case ty of
+    Lua.TypeString  -> Failure <$> Lua.peek idx
+    Lua.TypeBoolean -> do
+      b <- Lua.peek idx
+      return $ if b then Success else Failure "???"
+    _ -> do
+      s <- toString <$> Lua.tostring' idx
+      Lua.throwException ("not a test result: " ++ s)
diff --git a/src/Test/Tasty/Lua/Module.hs b/src/Test/Tasty/Lua/Module.hs
new file mode 100644
--- /dev/null
+++ b/src/Test/Tasty/Lua/Module.hs
@@ -0,0 +1,32 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-|
+Module      : Test.Tasty.Lua.Module
+Copyright   : © 2019 Albert Krewinkel
+License     : MIT
+Maintainer  : Albert Krewinkel <albert+hslua@zeitkraut.de>
+Stability   : alpha
+Portability : Requires TemplateHaskell
+
+Tasty Lua module, providing the functions necessary to write tasty tests
+in Lua scripts.
+-}
+module Test.Tasty.Lua.Module
+  ( pushModule )
+where
+
+import Data.ByteString (ByteString)
+import Data.FileEmbed
+import Foreign.Lua (Lua, NumResults, Status (OK), dostring, throwTopMessage)
+
+-- | Tasty Lua script
+tastyScript :: ByteString
+tastyScript = $(embedFile "tasty.lua")
+
+-- | Push the Aeson module on the Lua stack.
+pushModule :: Lua NumResults
+pushModule = do
+  result <- dostring tastyScript
+  if result == OK
+    then return 1
+    else throwTopMessage
+{-# INLINABLE pushModule #-}
diff --git a/src/Test/Tasty/Lua/Translate.hs b/src/Test/Tasty/Lua/Translate.hs
new file mode 100644
--- /dev/null
+++ b/src/Test/Tasty/Lua/Translate.hs
@@ -0,0 +1,57 @@
+{-|
+Module      : Test.Tasty.Lua.Translate
+Copyright   : © 2019 Albert Krewinkel
+License     : MIT
+Maintainer  : Albert Krewinkel <albert+hslua@zeitkraut.de>
+Stability   : alpha
+Portability : Requires TemplateHaskell
+
+Translate test results from Lua into a Tasty @'TestTree'@.
+-}
+module Test.Tasty.Lua.Translate
+  ( translateResultsFromFile
+  , pathFailure
+  )
+where
+
+import Foreign.Lua (Lua)
+import Test.Tasty.Lua.Core (Outcome (..), ResultTree (..), UnnamedTree (..),
+                            runTastyFile)
+import qualified Test.Tasty as Tasty
+import qualified Test.Tasty.Providers as Tasty
+
+-- | Run tasty.lua tests from the given file and translate the result
+-- into a mock Tasty @'TestTree'@.
+translateResultsFromFile :: FilePath -> Lua Tasty.TestTree
+translateResultsFromFile fp = do
+  result <- runTastyFile fp
+  case result of
+    Left errMsg -> return $ pathFailure fp errMsg
+    Right tree  -> return $ Tasty.testGroup fp (map testTree tree)
+
+-- | Report failure of testing a path.
+pathFailure :: FilePath -> String -> Tasty.TestTree
+pathFailure fp errMsg = Tasty.singleTest fp (MockTest (Failure errMsg))
+
+-- | Convert internal (tasty.lua) result tree format into Tasty tree.
+testTree :: ResultTree -> Tasty.TestTree
+testTree (ResultTree name tree) =
+  case tree of
+    SingleTest outcome -> Tasty.singleTest name (MockTest outcome)
+    TestGroup results  -> Tasty.testGroup name (map testTree results)
+
+-- | Mock test which just returns the predetermined outcome. An
+-- @'Outcome'@ can be treated like a Tasty test, as it encodes all
+-- necessary information. Usually, calling @'run'@ would trigger the
+-- execution of the test, but in this case, the test has already been
+-- run when the Lua script was executed.
+newtype MockTest = MockTest Outcome
+
+instance Tasty.IsTest MockTest where
+  run _ (MockTest outcome) _ = return $ case outcome of
+    Success     -> Tasty.testPassed ""
+    Failure msg -> Tasty.testFailed msg
+
+  testOptions = return []
+
+
diff --git a/tasty-lua.cabal b/tasty-lua.cabal
--- a/tasty-lua.cabal
+++ b/tasty-lua.cabal
@@ -1,5 +1,5 @@
 name:                tasty-lua
-version:             0.1.1
+version:             0.2.0
 synopsis:            Write tests in Lua, integrate into tasty.
 description:         Allow users to define tasty tests from Lua.
 homepage:            https://github.com/hslua/tasty-lua
@@ -17,7 +17,7 @@
 
 source-repository head
   type:              git
-  location:          https://github.com/hslua/hslua-module-tasty.git
+  location:          https://github.com/hslua/tasty-lua.git
 
 library
   build-depends:       base        >= 4.9    && < 5
@@ -27,6 +27,9 @@
                      , tasty       >= 1.2    && < 1.3
                      , text        >= 1.0    && < 1.3
   exposed-modules:     Test.Tasty.Lua
+                     , Test.Tasty.Lua.Core
+                     , Test.Tasty.Lua.Module
+                     , Test.Tasty.Lua.Translate
   hs-source-dirs:      src
   default-language:    Haskell2010
   ghc-options:         -Wall
diff --git a/test/test-tasty-lua.hs b/test/test-tasty-lua.hs
--- a/test/test-tasty-lua.hs
+++ b/test/test-tasty-lua.hs
@@ -17,14 +17,14 @@
 import System.FilePath ((</>))
 import Test.Tasty (TestTree, defaultMain, testGroup)
 import Test.Tasty.HUnit (assertEqual, testCase)
-import Test.Tasty.Lua (pushModule, testFileWith, testsFromFile)
+import Test.Tasty.Lua (pushModule, testLuaFile, translateResultsFromFile)
 
 import qualified Foreign.Lua as Lua
 
 main :: IO ()
 main = do
   luaTest <- withCurrentDirectory "test" . Lua.run $
-    testsFromFile "test-tasty.lua"
+    translateResultsFromFile "test-tasty.lua"
   defaultMain $ testGroup "tasty-hslua" [luaTest, tests]
 
 -- | HSpec tests for the Lua 'system' module
@@ -47,7 +47,7 @@
         Lua.dostring "require 'tasty'"
 
   , testGroup "testFileWith" $
-      [testFileWith ("test" </> "test-tasty.lua") Lua.run]
+      [testLuaFile Lua.run "test-tasty.lua" ("test" </> "test-tasty.lua")]
   ]
 
 assertEqual' :: (Show a, Eq a) => String -> a -> a -> Lua ()