additional test vectors for rewards calculation

cardano-foundation · Jan 21, 2020 · 8ec5ef6 · 8ec5ef6
1 parent 99dd776
commit 8ec5ef6
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Showing 2 changed files with 71 additions and 3 deletions.
diff --git a/lib/jormungandr/src/Cardano/Wallet/Jormungandr/Rewards.hs b/lib/jormungandr/src/Cardano/Wallet/Jormungandr/Rewards.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE TypeApplications #-}
 
 module Cardano.Wallet.Jormungandr.Rewards
     (
@@ -136,7 +137,7 @@ rewardsAt limit tax epochNo = q . taxCut tax . capDrawing limit . \case
     linearAbsorption RewardParams{rFixed,rRatio,rEpochStart,rEpochRate} =
         if a > c then 0 else c - a
       where
-        a = r * (n / e)
+        a = r * fromIntegral (floor @Double @Integer (n / e))
         c = fromIntegral rFixed
         r = ratio rRatio
         n = fromIntegral (ep - rEpochStart)
@@ -145,7 +146,7 @@ rewardsAt limit tax epochNo = q . taxCut tax . capDrawing limit . \case
     halvingAbsorption RewardParams{rFixed,rRatio,rEpochStart,rEpochRate} =
         c * a
       where
-        a = r * (n / e)
+        a = r ** fromIntegral (floor @Double @Integer (n / e))
         c = fromIntegral rFixed
         r = ratio rRatio
         n = fromIntegral (ep - rEpochStart)

diff --git a/lib/jormungandr/test/unit/Cardano/Wallet/Jormungandr/RewardsSpec.hs b/lib/jormungandr/test/unit/Cardano/Wallet/Jormungandr/RewardsSpec.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeApplications #-}
 
 {-# OPTIONS_GHC -fno-warn-orphans #-}
@@ -21,7 +22,7 @@ import Cardano.Wallet.Primitive.Types
 import Data.Quantity
     ( Quantity (..) )
 import Test.Hspec
-    ( Spec, describe, it )
+    ( Spec, describe, it, shouldBe )
 import Test.QuickCheck
     ( Arbitrary (..), choose, property, (===) )
 
@@ -48,5 +49,71 @@ spec = describe "rewardsAt" $ do
             rewardsAt drawingLimit treasuryTax epochNo rewardFormula
                 === Quantity 3452054796000
 
+    describe "Halving, C = 10000, ratio = 1/1, estart=10, rate=1" $ do
+        let rewardFormula = HalvingFormula $ RewardParams
+                { rFixed = 10000
+                , rEpochRate = 1
+                , rEpochStart = 10
+                , rRatio = Ratio 1 1
+                }
+        mapM_ (testReward noDrawingLimit noTreasuryTax rewardFormula) $ mconcat
+            [ [ (e, 0) | e <- [0..9]  ]
+            , [ (10, 10000) ]
+            , [ (11, 10000) ]
+            , [ (12, 10000) ]
+            , [ (13, 10000) ]
+            , [ (14, 10000) ]
+            ]
+
+    describe "Linear, C = 10000, ratio = 1000/1, estart=10, rate=2" $ do
+        let rewardFormula = LinearFormula $ RewardParams
+                { rFixed = 10000
+                , rEpochRate = 2
+                , rEpochStart = 10
+                , rRatio = Ratio 1000 1
+                }
+        mapM_ (testReward noDrawingLimit noTreasuryTax rewardFormula) $ mconcat
+            [ [ (e, 0) | e <- [0..9]  ]
+            , [ (10, 10000) ]
+            , [ (11, 10000) ]
+            , [ (12, 9000) ]
+            , [ (13, 9000) ]
+            , [ (14, 8000) ]
+            ]
+
+    describe "Halving, C = 10000, ratio = 1/2, estart=10, rate=2" $ do
+        let rewardFormula = HalvingFormula $ RewardParams
+                { rFixed = 10000
+                , rEpochRate = 2
+                , rEpochStart = 10
+                , rRatio = Ratio 1 2
+                }
+        mapM_ (testReward noDrawingLimit noTreasuryTax rewardFormula) $ mconcat
+            [ [ (e, 0) | e <- [0..9]  ]
+            , [ (10, 10000) ]
+            , [ (11, 10000) ]
+            , [ (12, 5000) ]
+            , [ (13, 5000) ]
+            , [ (14, 2500) ]
+            ]
+  where
+    testReward drawingLimit treasuryTax rewardFormula (epochNo, reward) =
+        it title $
+            rewardsAt drawingLimit treasuryTax epochNo rewardFormula
+                `shouldBe` Quantity reward
+      where
+        title = "epoch #" <> show (unEpochNo epochNo) <> " --> " <> show reward
+
+    noDrawingLimit =
+        ( RewardLimitNone
+        , Quantity 0
+        )
+
+    noTreasuryTax = TaxParameters
+        { taxFixed = 0
+        , taxRatio = Ratio 0 1
+        , taxLimit = Nothing
+        }
+
 instance Arbitrary EpochNo where
     arbitrary = EpochNo . fromIntegral @Int <$> choose (0, 1000)