diff --git a/servant-checked-exceptions.cabal b/servant-checked-exceptions.cabal
--- a/servant-checked-exceptions.cabal
+++ b/servant-checked-exceptions.cabal
@@ -1,5 +1,5 @@
 name:                servant-checked-exceptions
-version:             0.3.0.0
+version:             0.3.0.1
 synopsis:            Checked exceptions for Servant APIs.
 description:         Please see <https://github.com/cdepillabout/servant-checked-exceptions#readme README.md>.
 homepage:            https://github.com/cdepillabout/servant-checked-exceptions
@@ -118,29 +118,23 @@
   default-language:    Haskell2010
   ghc-options:         -Wall -threaded -rtsopts -with-rtsopts=-N
 
--- test-suite servant-checked-exceptions-test
---   type:                exitcode-stdio-1.0
---   main-is:             Spec.hs
---   other-modules:       Spec.ApiSpec
---                      , Spec.HelperFuncSpec
---                      , Spec.ServerSpec
---                      , Spec.TastyHelpers
---                      , Spec.TestDirLocation
---   hs-source-dirs:      test
---   build-depends:       base
---                      , bytestring
---                      , directory
---                      , filepath
---                      , hspec-wai
---                      , tasty
---                      , tasty-hspec
---                      , tasty-hunit
---                      , servant
---                      , servant-checked-exceptions
---                      , servant-server
---                      , wai
---   default-language:    Haskell2010
---   ghc-options:         -Wall -threaded -rtsopts -with-rtsopts=-N -fwarn-incomplete-uni-patterns -fwarn-incomplete-record-updates -fwarn-monomorphism-restriction
+test-suite servant-checked-exceptions-test
+  type:                exitcode-stdio-1.0
+  main-is:             Spec.hs
+  other-modules:
+  hs-source-dirs:      test
+  build-depends:       base
+                     , bytestring
+                     , hspec-wai
+                     , tasty
+                     , tasty-hspec
+                     , tasty-hunit
+                     , servant
+                     , servant-checked-exceptions
+                     , servant-server
+                     , wai
+  default-language:    Haskell2010
+  ghc-options:         -Wall -threaded -rtsopts -with-rtsopts=-N -fwarn-incomplete-uni-patterns -fwarn-incomplete-record-updates -fwarn-monomorphism-restriction
 
 source-repository head
   type:     git
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,136 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeOperators #-}
+
+module Main where
+
+import Control.Exception (Exception, SomeException, catch)
+import Data.Proxy (Proxy(Proxy))
+import Data.Type.Equality ((:~:)(Refl))
+import Data.Typeable (Typeable)
+import Network.Wai (Application)
+import Servant ((:<|>), (:>), Capture, Get, Handler, JSON, ServerT, serve)
+import Test.Hspec.Wai (get, shouldRespondWith, with)
+import Test.Tasty (TestTree, defaultMain, testGroup)
+import Test.Tasty.Hspec (testSpec, it)
+import Test.Tasty.HUnit ((@?=), assertFailure, testCase)
+
+import Servant.Checked.Exceptions
+       (Envelope, Throws, pureErrEnvelope, pureSuccEnvelope)
+
+main :: IO ()
+main = do
+  tests <- testsIO
+  defaultMain tests
+
+testsIO :: IO TestTree
+testsIO = do
+  serverTests <- serverTestsIO
+  pure $
+    testGroup
+      "tests"
+      [ hasServerInstanceTests
+      , serverTests
+      ]
+
+-------------
+-- Helpers --
+-------------
+
+type Selector e = e -> Bool
+
+anyException :: Selector SomeException
+anyException _ = True
+
+-- | Extra HUnit assertion to make sure an expression throws an exception.
+assertThrows
+  :: forall e a.
+     (Exception e, Typeable e)
+  => IO a -> Selector e -> IO ()
+assertThrows ioAction selector = do
+  didCatch <- catch (ioAction *> pure False) (pure . selector)
+  case didCatch of
+    False ->
+      assertFailure "expecting an exception, but no exception occurred"
+    True -> pure ()
+
+-- | Infix version of 'assertThrows'.
+(@!)
+  :: (Exception e, Typeable e)
+  => IO a -> Selector e -> IO ()
+(@!) = assertThrows
+
+infix 1 @!
+
+------------------------------
+-- HasServer instance tests --
+------------------------------
+
+type ApiThrows = Throws String :> Get '[JSON] Int
+
+checkApiThrows
+  :: ServerT ApiThrows m :~: m (Envelope '[String] Int)
+checkApiThrows = Refl
+
+
+type ApiDoubleThrows = Throws String :> Throws Double :> Get '[JSON] Int
+
+checkApiDoubleThrows
+  :: ServerT ApiDoubleThrows m :~: m (Envelope '[String, Double] Int)
+checkApiDoubleThrows = Refl
+
+
+type ApiThrowsBeforeCapture =
+  Throws String :> Capture "foobar" Double :> Get '[JSON] Int
+
+checkApiThrowsBeforeCapture
+  :: ServerT ApiThrowsBeforeCapture m :~: (Double -> m (Envelope '[String] Int))
+checkApiThrowsBeforeCapture = Refl
+
+
+type ApiThrowsBeforeMulti =
+  Throws String :> (Get '[JSON] Int :<|> Get '[JSON] Double)
+
+checkApiThrowsBeforeMulti
+  :: ServerT ApiThrowsBeforeMulti m :~:
+     (m (Envelope '[String] Int) :<|> m (Envelope '[String] Double))
+checkApiThrowsBeforeMulti = Refl
+
+
+hasServerInstanceTests :: TestTree
+hasServerInstanceTests =
+  testGroup
+    "HasServer instances"
+    [ testCase "single Throws" $ checkApiThrows @?= Refl
+    , testCase "double Throws" $ checkApiDoubleThrows @?= Refl
+    , testCase "Throws before Capture" $ checkApiThrowsBeforeCapture @?= Refl
+    , testCase "Throws before (:<|>)" $ checkApiThrowsBeforeMulti @?= Refl
+    ]
+
+------------------
+-- Server tests --
+------------------
+
+type TestApi = Capture "foobar" Double :> Throws Int :> Get '[JSON] String
+
+server :: ServerT TestApi Handler
+server = helloWorldGet
+
+helloWorldGet :: Double -> Handler (Envelope '[Int] String)
+helloWorldGet double =
+  if double < 0
+    then pureErrEnvelope (0 :: Int)
+    else pureSuccEnvelope "success"
+
+app :: Application
+app = serve (Proxy :: Proxy TestApi) server
+
+serverTestsIO :: IO TestTree
+serverTestsIO =
+  testSpec "server" $
+    with (pure app) $ do
+      it "handler can return error envelope" $
+        get "/-5" `shouldRespondWith` "{\"err\":0}"
+      it "handler can return success envelope" $
+        get "/10" `shouldRespondWith` "{\"data\":\"success\"}"