From a203637456408c6a19c0ea82516243f57d2c6e22 Mon Sep 17 00:00:00 2001
From: Vadim <korobeinikovv@mail.ru>
Date: Mon, 13 Sep 2021 21:54:07 +0300
Subject: [PATCH] #69 : Add unit tests

---
 src/utils/page.js      | 2 +-
 src/utils/page.test.js | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/utils/page.js b/src/utils/page.js
index f66051f..d0e0a98 100644
--- a/src/utils/page.js
+++ b/src/utils/page.js
@@ -157,7 +157,7 @@ export function getPartialPageSize({
   while(true) {
     const diff = particlesCountWithoutClones - particlesCount - overlap
     if (diff < particlesToShow) {
-      return diff
+      return Math.max(diff, 0) // show: 2; scroll: 3, n: 5 => -1
     }
     particlesCount += particlesToShow + overlap
   }
diff --git a/src/utils/page.test.js b/src/utils/page.test.js
index 6fad144..4c451ea 100644
--- a/src/utils/page.test.js
+++ b/src/utils/page.test.js
@@ -40,6 +40,11 @@ describe('getPartialPageSize', () => {
       particlesToShow: 2,
       particlesToScroll: 2,
       expected: 0,
+    }, {
+      particlesCountWithoutClones: 5,
+      particlesToShow: 2,
+      particlesToScroll: 3,
+      expected: 0,
     }]
 
     testCases.forEach(({