Implement saving+loading the game

Implement ToJSON and FromJSON for all of the various pieces of the game
state, and add a pair of functions saveGame/loadGame implementing a
prism to save the game as zlib-compressed JSON. To test this, there's
now Arbitrary, CoArbitrary, and Function instances for all the parts of
the game state - to get around circular imports with the concrete
entities this unfortunately is happening via orphan instances, plus an
hs-boot file to break a circular import that was just a little too hard
to remove by moving things around. Ugh.

1 files changed, 9 insertions, 2 deletions

diff --git a/test/Xanthous/Data/EntityMapSpec.hs b/test/Xanthous/Data/EntityMapSpec.hs
index 2e9714a44eb7..53f03020f346 100644
--- a/test/Xanthous/Data/EntityMapSpec.hs
+++ b/test/Xanthous/Data/EntityMapSpec.hs
@@ -2,9 +2,11 @@
 --------------------------------------------------------------------------------
 module Xanthous.Data.EntityMapSpec where
 --------------------------------------------------------------------------------
-import Test.Prelude
+import           Test.Prelude
 --------------------------------------------------------------------------------
-import Xanthous.Data.EntityMap
+import qualified Data.Aeson as JSON
+--------------------------------------------------------------------------------
+import           Xanthous.Data.EntityMap
 --------------------------------------------------------------------------------
 
 main :: IO ()
@@ -30,4 +32,9 @@ test = localOption (QuickCheckTests 20)
         then (em₁ == em₃)
         else True
     ]
+  , testGroup "JSON encoding/decoding"
+    [ testProperty "Preserves IDs" $ \(em :: EntityMap Int) ->
+        let Just em' = JSON.decode $ JSON.encode em
+        in toEIDsAndPositioned em' === toEIDsAndPositioned em
+    ]
   ]