feat(xanthous): Describe *where* the item is in the inventory

When describing items in the inventory, both in detail and when
producing menus from those items, describe not just the item itself but
also *where* in the inventory the item is (either in the backpack, or
wielded in either or both of the hands). This uses a new
InventoryPosition datatype, and a method to get a list of items in the
inventory associated with their inventory position. When *removing*
items from the inventory (to wield, drop, or eat them), we want to make
sure we remove from the right position, so this also introduces
a `removeItemAtPosition` method to make that happen correctly.

Finally, some of the tests for this stuff was getting really slow - I
narrowed this down to runaway arbitrary generation for message
Templates, so I've tweaked the Arbitrary instance for that type to
generate smaller values.

Change-Id: I24e9948adae24b0ca9bf13955602108ca9079dcc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3228
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

users/grfn/xanthous/test/Xanthous/Entities/CharacterSpec.hs

@@ -3,6 +3,7 @@
 module Xanthous.Entities.CharacterSpec (main, test) where
 --------------------------------------------------------------------------------
 import           Test.Prelude
+import           Data.Vector.Lens (toVectorOf)
 --------------------------------------------------------------------------------
 import           Xanthous.Entities.Character
 import           Xanthous.Util (endoTimes)
@@ -21,4 +22,21 @@ test = testGroup "Xanthous.Entities.CharacterSpec"
           in _knuckleDamage knuckles' @?= 5
       ]
     ]
+  , testGroup "Inventory"
+    [ testProperty "items === itemsWithPosition . _2" $ \inv ->
+        inv ^.. items === inv ^.. itemsWithPosition . _2
+    , testGroup "removeItemFromPosition" $
+      let rewield w inv =
+            let (old, inv') = inv & wielded <<.~ w
+            in inv' & backpack <>~ toVectorOf (wieldedItems . wieldedItem) old
+      in [ (Backpack, \item -> backpack %~ (item ^. wieldedItem <|))
+         , (LeftHand, rewield . inLeftHand)
+         , (RightHand, rewield . inRightHand)
+         , (BothHands, rewield . review doubleHanded)
+         ] <&> \(pos, addItem) ->
+           testProperty (show pos) $ \inv item ->
+             let inv' = addItem item inv
+                 inv'' = removeItemFromPosition pos (item ^. wieldedItem) inv'
+             in inv'' ^.. items === inv ^.. items
+    ]
   ]

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

@@ -38,7 +38,7 @@ test = testGroup "Xanthous.Messages"
           let
             Right tpl = compileMustacheText "foo" "bar"
             msg = Single tpl
-            mm = Nested $ [("foo", Direct msg)]
+            mm = Nested [("foo", Direct msg)]
           in mm ^? ix ["foo"] @?= Just msg
         ]
     , testGroup "lookupMessage"
@@ -50,4 +50,10 @@ test = testGroup "Xanthous.Messages"
   , testGroup "Messages"
     [ testCase "are all valid" $ messages `deepseq` pure ()
     ]
+
+  , testGroup "Template"
+    [ testGroup "eq"
+      [ testProperty "reflexive" $ \(tpl :: Template) -> tpl == tpl
+      ]
+    ]
   ]

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

@@ -34,4 +34,10 @@ test = testGroup "Xanthous.Util"
     [ testCase "_1 += 1"
       $ execState (modifyKL _1 $ pure . succ) (1 :: Int, 2 :: Int) @?= (2, 2)
     ]
+  , testGroup "removeFirst"
+    [ testCase "example" $
+      removeFirst @[Int] (> 5) [1..10] @?= [1, 2, 3, 4, 5, 7, 8, 9, 10]
+    , testProperty "the result is the right length" $ \(xs :: [Int]) p ->
+        length (removeFirst p xs) `elem` [length xs, length xs - 1]
+    ]
   ]