From b82e4c5cf1bcf68fa1c1f66b40a04ba1e0351ec5 Mon Sep 17 00:00:00 2001
From: simov <simeonvelichkov@gmail.com>
Date: Wed, 7 Feb 2018 23:08:16 +0200
Subject: [PATCH] Update test and snippet description with easier to understand
 examples

---
 snippets/stableSort.md             | 62 ++++++++++++++++++++++++++----
 test/stableSort/stableSort.test.js | 44 +++++++++++++++++----
 2 files changed, 90 insertions(+), 16 deletions(-)

diff --git a/snippets/stableSort.md b/snippets/stableSort.md
index 96b352b08..e02c3b3dc 100644
--- a/snippets/stableSort.md
+++ b/snippets/stableSort.md
@@ -14,14 +14,60 @@ const stableSort = (arr, compare) =>
 ```
 
 ```js
-const str = 'abcdefghijklmnopqrstuvwxyz';
-const compare = (a, b) => ~~(str.indexOf(b) / 2.3) - ~~(str.indexOf(a) / 2.3);
+// sorted by weight
+const input = [
+  { height: 100, weight: 80 },
+  { height: 90, weight: 90 },
+  { height: 70, weight: 95 },
+  { height: 100, weight: 100 },
+  { height: 80, weight: 110 },
+  { height: 110, weight: 115 },
+  { height: 100, weight: 120 },
+  { height: 70, weight: 125 },
+  { height: 70, weight: 130 },
+  { height: 100, weight: 135 },
+  { height: 75, weight: 140 },
+  { height: 70, weight: 140 }
+];
 
-// default Array.sort() is unstable in Chrome and NodeJS + modifies the input array
-var arr1 = str.split('');
-console.log(arr1.sort(compare).join('') === 'xyzvwtursopqmnklhijfgdeabc'); // false
+const compare = (a, b) => a.height - b.height;
 
-// stable sort + returns new array
-const arr2 = str.split('');
-console.log(stableSort(arr2, compare).join('') === 'xyzvwtursopqmnklhijfgdeabc'); // true
+// stable - sorted by height using stableSort()
+// Items with the same height are still sorted by weight which means they preserved their relative order.
+stableSort(input, compare);
+/*
+  [
+    { height: 70, weight: 95 },
+    { height: 70, weight: 125 },
+    { height: 70, weight: 130 },
+    { height: 70, weight: 140 },
+    { height: 75, weight: 140 },
+    { height: 80, weight: 110 },
+    { height: 90, weight: 90 },
+    { height: 100, weight: 80 },
+    { height: 100, weight: 100 },
+    { height: 100, weight: 120 },
+    { height: 100, weight: 135 },
+    { height: 110, weight: 115 }
+  ]
+*/
+
+// unstable - sorted by height using Array.sort()
+input.sort(compare);
+/*
+  [
+    { height: 70, weight: 140},
+    { height: 70, weight: 95 },
+    { height: 70, weight: 125 },
+    { height: 70, weight: 130 },
+    { height: 75, weight: 140 },
+    { height: 80, weight: 110 },
+    { height: 90, weight: 90 },
+    { height: 100, weight: 100 },
+    { height: 100, weight: 80 },
+    { height: 100, weight: 135 },
+    { height: 100, weight: 120 },
+    { height: 110, weight: 115 }
+  ]
+*/
 ```
diff --git a/test/stableSort/stableSort.test.js b/test/stableSort/stableSort.test.js
index 7c41e06f3..cd4a66e9f 100644
--- a/test/stableSort/stableSort.test.js
+++ b/test/stableSort/stableSort.test.js
@@ -10,16 +10,44 @@ test('Testing stableSort', (t) => {
   //t.false(stableSort(args..), 'Expected');
   //t.throws(stableSort(args..), 'Expected');
   
-  // test if js engine's Array#sort implementation is stable
-  // https://gist.github.com/leeoniya/5816476
-  const str = 'abcdefghijklmnopqrstuvwxyz';
-  const compare = (a, b) => ~~(str.indexOf(b) / 2.3) - ~~(str.indexOf(a) / 2.3);
+  // sorted by weight
+  const input = [
+    { height: 100, weight: 80 },
+    { height: 90, weight: 90 },
+    { height: 70, weight: 95 },
+    { height: 100, weight: 100 },
+    { height: 80, weight: 110 },
+    { height: 110, weight: 115 },
+    { height: 100, weight: 120 },
+    { height: 70, weight: 125 },
+    { height: 70, weight: 130 },
+    { height: 100, weight: 135 },
+    { height: 75, weight: 140 },
+    { height: 70, weight: 140 }
+  ]
 
-  const input = str.split('');
-  const output = stableSort(input, compare);
+  // sorted by height (using stableSort)
+  const target = [
+    { height: 70, weight: 95 },
+    { height: 70, weight: 125 },
+    { height: 70, weight: 130 },
+    { height: 70, weight: 140 },
+    { height: 75, weight: 140 },
+    { height: 80, weight: 110 },
+    { height: 90, weight: 90 },
+    { height: 100, weight: 80 },
+    { height: 100, weight: 100 },
+    { height: 100, weight: 120 },
+    { height: 100, weight: 135 },
+    { height: 110, weight: 115 }
+  ]
 
-  t.equal(output.join(''), 'xyzvwtursopqmnklhijfgdeabc');
-  t.notDeepEqual(input, output);
+  const compare = (a, b) => a.height - b.height;
+
+  // stable
+  t.deepEqual(stableSort(input, compare), target);
+  // unstable
+  t.notDeepEqual(input.sort(compare), target);
 
   t.end();
 });
\ No newline at end of file