1 files changed, 25 insertions, 0 deletions
diff --git a/users/grfn/xanthous/test/Xanthous/RandomSpec.hs b/users/grfn/xanthous/test/Xanthous/RandomSpec.hs
new file mode 100644
index 000000000000..187336f08650
--- /dev/null
+++ b/users/grfn/xanthous/test/Xanthous/RandomSpec.hs
@@ -0,0 +1,25 @@
+--------------------------------------------------------------------------------
+module Xanthous.RandomSpec (main, test) where
+--------------------------------------------------------------------------------
+import Test.Prelude
+--------------------------------------------------------------------------------
+import Control.Monad.Random
+--------------------------------------------------------------------------------
+import Xanthous.Random
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = defaultMain test
+
+test :: TestTree
+test = testGroup "Xanthous.Random"
+  [ testGroup "chooseSubset"
+    [ testProperty "chooses a subset"
+      $ \(l :: [Int]) (Positive (r :: Double)) -> randomTest $ do
+        ss <- chooseSubset r l
+        pure $ all (`elem` l) ss
+
+    ]
+  ]
+  where
+    randomTest prop = evalRandT prop . mkStdGen =<< arbitrary