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diff --git a/tests/PropMime.hs b/tests/PropMime.hs
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+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# OPTIONS_GHC -fno-warn-unused-imports #-}
+
+module PropMime where
+
+import Data.Aeson
+import Data.Aeson.Types (parseEither)
+import Data.Monoid ((<>))
+import Data.Typeable (Proxy(..), typeOf, Typeable)
+import qualified Data.ByteString.Lazy.Char8 as BL8
+import Test.Hspec
+import Test.QuickCheck
+import Test.QuickCheck.Property
+import Test.Hspec.QuickCheck (prop)
+
+import G4fClient.MimeTypes
+
+import ApproxEq
+
+-- * Type Aliases
+
+type ArbitraryMime mime a = ArbitraryRoundtrip (MimeUnrender mime) (MimeRender mime) a
+
+type ArbitraryRoundtrip from to a = (from a, to a, Arbitrary' a)
+
+type Arbitrary' a = (Arbitrary a, Show a, Typeable a)
+
+-- * Mime
+
+propMime
+  :: forall a b mime.
+     (ArbitraryMime mime a, Testable b)
+  => String -> (a -> a -> b) -> mime -> Proxy a -> Spec
+propMime eqDescr eq m _ =
+  prop
+    (show (typeOf (undefined :: a)) <> " " <> show (typeOf (undefined :: mime)) <> " roundtrip " <> eqDescr) $
+  \(x :: a) ->
+     let rendered = mimeRender' m x
+         actual = mimeUnrender' m rendered
+         expected = Right x
+         failMsg =
+           "ACTUAL: " <> show actual <> "\nRENDERED: " <> BL8.unpack rendered
+     in counterexample failMsg $
+        either reject property (eq <$> actual <*> expected)
+  where
+    reject = property . const rejected
+
+propMimeEq :: (ArbitraryMime mime a, Eq a) => mime -> Proxy a -> Spec
+propMimeEq = propMime "(EQ)" (==)