Add 'users/glittershark/xanthous/' from commit '53b56744f4335c038724a1bcffc27a7eb8cf6a6d' r/978

git-subtree-dir: users/glittershark/xanthous
git-subtree-mainline: 91f53f02d8479303910abfd3f3690d3ef27e6c4b
git-subtree-split: 53b56744f4335c038724a1bcffc27a7eb8cf6a6d

1 files changed, 28 insertions, 0 deletions

diff --git a/users/glittershark/xanthous/test/Xanthous/UtilSpec.hs b/users/glittershark/xanthous/test/Xanthous/UtilSpec.hs
new file mode 100644
index 000000000000..8538ea5098ba
--- /dev/null
+++ b/users/glittershark/xanthous/test/Xanthous/UtilSpec.hs
@@ -0,0 +1,28 @@
+module Xanthous.UtilSpec (main, test) where
+
+import Test.Prelude
+import Xanthous.Util
+
+main :: IO ()
+main = defaultMain test
+
+test :: TestTree
+test = testGroup "Xanthous.Util"
+  [ testGroup "smallestNotIn"
+    [ testCase "examples" $ do
+        smallestNotIn [7 :: Word, 3, 7] @?= 0
+        smallestNotIn [7 :: Word, 0, 1, 3, 7] @?= 2
+    , testProperty "returns an element not in the list" $ \(xs :: [Word]) ->
+        smallestNotIn xs `notElem` xs
+    , testProperty "pred return is in the list" $ \(xs :: [Word]) ->
+        let res = smallestNotIn xs
+        in res /= 0 ==> pred res `elem` xs
+    , testProperty "ignores order" $ \(xs :: [Word]) ->
+        forAll (shuffle xs) $ \shuffledXs ->
+          smallestNotIn xs === smallestNotIn shuffledXs
+    ]
+  , testGroup "takeWhileInclusive"
+    [ testProperty "takeWhileInclusive (const True) ≡ id"
+      $ \(xs :: [Int]) -> takeWhileInclusive (const True) xs === xs
+    ]
+  ]