Fix Bfx.mkOrder rounding on Sell

Author: functora

pub/bfx/bfx.cabal

@@ -192,6 +192,7 @@ test-suite bfx-test
       , base               >=4.7 && <5
       , base16-bytestring
       , bytestring
+      , conduit
       , containers
       , cryptonite
       , envparse

pub/bfx/src/Bfx.hs

@@ -564,14 +564,14 @@ mkOrder args = do
       pure
       $ mkOrderNetBaseAmt args
   grossBaseAmt <-
-    case bos of
-      Buy ->
-        tweakMoneyAmount Buy
-          . MoneyAmount
-          $ unMoneyAmount netBaseAmt
-          / (1 - unFeeRate (mkOrderFee args))
-      Sell ->
-        pure netBaseAmt
+    tweakMoneyAmount bos
+      $ case bos of
+        Buy ->
+          MoneyAmount
+            $ unMoneyAmount netBaseAmt
+            / (1 - unFeeRate (mkOrderFee args))
+        Sell ->
+          netBaseAmt
   price <-
     mkOrderMarketAveragePrice
       args

pub/bfx/test/BfxSpec.hs

@@ -126,6 +126,9 @@ spec = before sysEnv $ do
         & #limit
         .~ Just 5
     res `shouldSatisfy` isRight
+  it "roundMoneyAmount" . const $ do
+    amt <- roundMoneyAmount . MoneyAmount $ 3391591 % 10000000000
+    amt `shouldBe` MoneyAmount (8479 % 25000000)
   it "mkOrder" . const $ do
     let req =
           Bfx.MkOrder