diff --git a/yesod-json/test/Spec.hs b/yesod-json/test/Spec.hs
new file mode 100644
index 00000000..7ed8c3dd
--- /dev/null
+++ b/yesod-json/test/Spec.hs
@@ -0,0 +1,47 @@
+{-# LANGUAGE OverloadedStrings, TemplateHaskell, QuasiQuotes, TypeFamilies, MultiParamTypeClasses #-}
+import Yesod.Core
+import Yesod.Json
+import Test.Hspec
+import qualified Data.Map as Map
+import Network.Wai.Test
+import Data.Text (Text)
+
+data App = App
+
+mkYesod "App" [parseRoutes|
+/ HomeR GET
+|]
+
+instance Yesod App
+
+getHomeR :: Handler RepPlain
+getHomeR = do
+    val <- parseJsonBody_
+    case Map.lookup ("foo" :: Text) val of
+        Nothing -> invalidArgs ["foo not found"]
+        Just foo -> return $ RepPlain $ toContent (foo :: Text)
+
+main :: IO ()
+main = do
+    app <- toWaiApp App
+    hspec $ describe "Yesod.Json" $ do
+        it "parses valid content" $ flip runSession app $ do
+            sres <- srequest SRequest
+                { simpleRequest = defaultRequest
+                , simpleRequestBody = "{\"foo\":\"bar\"}"
+                }
+            assertStatus 200 sres
+            assertBody "bar" sres
+        it "400 for bad JSON" $ flip runSession app $ do
+            sres <- srequest SRequest
+                { simpleRequest = defaultRequest
+                , simpleRequestBody = "{\"foo\":\"bar\""
+                }
+            assertStatus 400 sres
+        it "400 for bad structure" $ flip runSession app $ do
+            sres <- srequest SRequest
+                { simpleRequest = defaultRequest
+                , simpleRequestBody = "{\"foo2\":\"bar\"}"
+                }
+            assertStatus 400 sres
+            assertBodyContains "foo not found" sres