From 2af4b3e9212d623be5f335856b7d8600a0d1bf58 Mon Sep 17 00:00:00 2001
From: Brian Hicks <brian@brianthicks.com>
Date: Thu, 10 Sep 2020 23:00:06 -0500
Subject: [PATCH] test my expectations of k-factor changes

---
 tests/EloTest.elm | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tests/EloTest.elm b/tests/EloTest.elm
index daa051e..d395f87 100644
--- a/tests/EloTest.elm
+++ b/tests/EloTest.elm
@@ -60,4 +60,17 @@ newRating =
                         Elo.newRating Elo.sensitiveKFactor player WonAgainst favorite
                 in
                 newAgainstEqual |> Expect.lessThan newAgainstFavorite
+        , fuzz2 ratingFuzzer (Fuzz.intRange 1 32) "a higher k-value produces a larger score difference than a lower one" <|
+            \player kFactorIncrease ->
+                let
+                    opponent =
+                        player + 100
+
+                    ( newWithLowKFactor, _ ) =
+                        Elo.newRating Elo.sensitiveKFactor player WonAgainst opponent
+
+                    ( newWithHighKFactor, _ ) =
+                        Elo.newRating (Elo.sensitiveKFactor + kFactorIncrease) player WonAgainst opponent
+                in
+                newWithLowKFactor |> Expect.lessThan newWithHighKFactor
         ]