diff --git a/CG2.cabal b/CG2.cabal
index 24b2005..e308456 100644
--- a/CG2.cabal
+++ b/CG2.cabal
@@ -160,6 +160,7 @@ executable Test
                        Parser.Meshparser
                        Parser.PathParser
                        QueueEx
+                       Test.MyPrelude
                        Test.Vector
 
 
diff --git a/Test/MyPrelude.hs b/Test/MyPrelude.hs
new file mode 100644
index 0000000..76ec682
--- /dev/null
+++ b/Test/MyPrelude.hs
@@ -0,0 +1,43 @@
+{-# OPTIONS_HADDOCK ignore-exports #-}
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
+
+module Test.MyPrelude where
+
+import MyPrelude
+import Test.QuickCheck
+
+
+splitByProp1 :: Positive Int
+             -> NonEmptyList (Positive Int)
+             -> NonEmptyList (Positive Int)
+             -> Bool
+splitByProp1 (Positive x) (NonEmpty xs) (NonEmpty ys) =
+  splitBy (== negate x) (xs' ++ [negate x] ++ ys') == [xs', ys']
+  where
+    xs' = fmap getPositive xs
+    ys' = fmap getPositive ys
+
+
+splitByProp2 :: Positive Int
+             -> NonEmptyList (Positive Int)
+             -> NonEmptyList (Positive Int)
+             -> Bool
+splitByProp2 (Positive x) (NonEmpty xs) (NonEmpty ys) =
+  splitBy (== negate x) (xs' ++ [negate x] ++ ys' ++ [negate x] ++ xs')
+  ==
+  [xs', ys', xs']
+  where
+    xs' = fmap getPositive xs
+    ys' = fmap getPositive ys
+
+
+-- splitting by an element that is not in the list should leave the list
+-- untouched
+splitByProp3 :: Positive Int
+             -> NonEmptyList (Positive Int)
+             -> Bool
+splitByProp3 (Positive x) (NonEmpty xs) =
+  splitBy (== negate x) xs' == [xs']
+  where
+    xs' = fmap getPositive xs
+
diff --git a/TestMain.hs b/TestMain.hs
index 74f0658..0f8df40 100644
--- a/TestMain.hs
+++ b/TestMain.hs
@@ -2,6 +2,7 @@
 
 
 import Test.QuickCheck
+import Test.MyPrelude
 import Test.Vector
 
 
@@ -51,3 +52,7 @@ main = do
   putStrLn "testing det:"
   deepCheck detProp1
   deepCheck detProp2
+  putStrLn "testing splitBy"
+  deepCheck splitByProp1
+  deepCheck splitByProp2
+  deepCheck splitByProp3