From 377a19eebe0ab851bea2dac4a54db5caad58cfe7 Mon Sep 17 00:00:00 2001
From: KtorZ <matthias.benkort@gmail.com>
Date: Tue, 7 May 2019 16:31:34 +0200
Subject: [PATCH] fix 'slotRatio' case where the numerator is further than the
 denominator

---
 lib/core/src/Cardano/Wallet/Primitive/Types.hs           | 2 +-
 lib/core/test/unit/Cardano/Wallet/Primitive/TypesSpec.hs | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/core/src/Cardano/Wallet/Primitive/Types.hs b/lib/core/src/Cardano/Wallet/Primitive/Types.hs
index 818cf8bafd5..924eecca078 100644
--- a/lib/core/src/Cardano/Wallet/Primitive/Types.hs
+++ b/lib/core/src/Cardano/Wallet/Primitive/Types.hs
@@ -593,7 +593,7 @@ slotRatio (SlotId ep0 sl0) (SlotId ep1 sl1) =
         n0 = flat ep0 sl0
         n1 = flat ep1 sl1
         tolerance = 5
-    in if distance n0 n1 < tolerance then
+    in if distance n0 n1 < tolerance || n0 >= n1 then
         maxBound
     else
         Quantity $ toEnum $ fromIntegral $ (100 * n0) `div` n1
diff --git a/lib/core/test/unit/Cardano/Wallet/Primitive/TypesSpec.hs b/lib/core/test/unit/Cardano/Wallet/Primitive/TypesSpec.hs
index 52a589eb85f..321d78348f8 100644
--- a/lib/core/test/unit/Cardano/Wallet/Primitive/TypesSpec.hs
+++ b/lib/core/test/unit/Cardano/Wallet/Primitive/TypesSpec.hs
@@ -35,9 +35,12 @@ import Cardano.Wallet.Primitive.Types
     , isValidCoin
     , restrictedBy
     , restrictedTo
+    , slotRatio
     , walletNameMaxLength
     , walletNameMinLength
     )
+import Control.DeepSeq
+    ( deepseq )
 import Control.Monad
     ( replicateM )
 import Crypto.Hash
@@ -138,6 +141,9 @@ spec = do
             \      <~ 19999800000 @ DdzFFzCq...UfLEFu1q\n"
                 === pretty @_ @Text block
 
+    describe "slotRatio" $ do
+        it "works for any two slots" $ property $ \sl0 sl1 ->
+            slotRatio sl0 sl1 `deepseq` ()
 
     describe "Negative cases for types decoding" $ do
         it "fail fromText @Address \"0000\"" $ do