refactor(users/glittershark): Rename to grfn

Rename my //users directory and all places that refer to glittershark to
grfn, including nix references and documentation.

This may require some extra attention inside of gerrit's database after
it lands to allow me to actually push things.

Change-Id: I4728b7ec2c60024392c1c1fa6e0d4a59b3e266fa
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2933
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: lukegb <lukegb@tvl.fyi>
Reviewed-by: glittershark <grfn@gws.fyi>

users/grfn/xanthous/test/Xanthous/GameSpec.hs

@@ -0,0 +1,55 @@
+module Xanthous.GameSpec where
+
+import Test.Prelude hiding (Down)
+import Xanthous.Game
+import Xanthous.Game.State
+import Control.Lens.Properties
+import Xanthous.Data (move, Direction(Down))
+import Xanthous.Data.EntityMap (atPosition)
+
+main :: IO ()
+main = defaultMain test
+
+test :: TestTree
+test
+  = localOption (QuickCheckTests 10)
+  . localOption (QuickCheckMaxSize 10)
+  $ testGroup "Xanthous.Game"
+  [ testGroup "positionedCharacter"
+    [ testProperty "lens laws" $ isLens positionedCharacter
+    , testCase "updates the position of the character" $ do
+      initialGame <- getInitialState
+      let initialPos = initialGame ^. characterPosition
+          updatedGame = initialGame & characterPosition %~ move Down
+          updatedPos = updatedGame ^. characterPosition
+      updatedPos @?= move Down initialPos
+      updatedGame ^. entities . atPosition initialPos @?= fromList []
+      updatedGame ^. entities . atPosition updatedPos
+        @?= fromList [SomeEntity $ initialGame ^. character]
+    ]
+  , testGroup "characterPosition"
+    [ testProperty "lens laws" $ isLens characterPosition
+    ]
+  , testGroup "character"
+    [ testProperty "lens laws" $ isLens character
+    ]
+  , testGroup "MessageHistory"
+    [ testGroup "MonoComonad laws"
+      [ testProperty "oextend oextract ≡ id"
+        $ \(mh :: MessageHistory) -> oextend oextract mh === mh
+      , testProperty "oextract ∘ oextend f ≡ f"
+        $ \(mh :: MessageHistory) f -> (oextract . oextend f) mh === f mh
+      , testProperty "oextend f ∘ oextend g ≡ oextend (f . oextend g)"
+        $ \(mh :: MessageHistory) f g ->
+          (oextend f . oextend g) mh === oextend (f . oextend g) mh
+      ]
+    ]
+  , testGroup "Saving the game"
+    [ testProperty "forms a prism" $ isPrism saved
+    , testProperty "round-trips" $ \gs ->
+        loadGame (saveGame gs) === Just gs
+    , testProperty "preserves the character ID" $ \gs ->
+        let Just gs' = loadGame $ saveGame gs
+        in gs' ^. character === gs ^. character
+    ]
+  ]