Fix an injectivity issue with saving the game

Fix an injectivity issue with JSON-encoding the entity map that was
causing the game saving to not properly round-trip. As part of this,
there's a refactor to the internals of the entity map to use sets
instead of vectors, which should also get us a nice perf boost.

1 files changed, 9 insertions, 1 deletions

diff --git a/test/Xanthous/Data/EntityMapSpec.hs b/test/Xanthous/Data/EntityMapSpec.hs
index 53f03020f346..88e0d0d7712c 100644
--- a/test/Xanthous/Data/EntityMapSpec.hs
+++ b/test/Xanthous/Data/EntityMapSpec.hs
@@ -33,7 +33,15 @@ test = localOption (QuickCheckTests 20)
         else True
     ]
   , testGroup "JSON encoding/decoding"
-    [ testProperty "Preserves IDs" $ \(em :: EntityMap Int) ->
+    [ testProperty "round-trips" $ \(em :: EntityMap Int) ->
+        let em' = JSON.decode (JSON.encode em)
+        in counterexample (show (em' ^? _Just . lastID, em ^. lastID
+                                , em' ^? _Just . byID == em ^. byID . re _Just
+                                , em' ^? _Just . byPosition == em ^. byPosition . re _Just
+                                , em' ^? _Just . _EntityMap == em ^. _EntityMap . re _Just
+                                ))
+           $ em' === Just em
+    , testProperty "Preserves IDs" $ \(em :: EntityMap Int) ->
         let Just em' = JSON.decode $ JSON.encode em
         in toEIDsAndPositioned em' === toEIDsAndPositioned em
     ]