From 9513bcd77a9eb1ab1090ddb942642e0d438a8b14 Mon Sep 17 00:00:00 2001
From: merelymyself <88221256+merelymyself@users.noreply.github.com>
Date: Fri, 22 Apr 2022 00:28:29 +0800
Subject: [PATCH] merge: WhileLoopFactorial: Optimize and add tests (#992)

* Optimised the factorial function.

There was previously an unnecessary check for if the number was 0 or 1.

* Create WhileLoopFactorial.test.js

The test was not present previously.

* result *= num

* Update WhileLoopFactorial.test.js

* testFactorial function

* Space for formatting.

* should fix the formatting issues. I was having trouble with npx standard, so I just used the online verifier at https://standardjs.com/demo.html
---
 Maths/WhileLoopFactorial.js           | 10 ++++------
 Maths/test/WhileLoopFactorial.test.js | 12 ++++++++++++
 2 files changed, 16 insertions(+), 6 deletions(-)
 create mode 100644 Maths/test/WhileLoopFactorial.test.js

diff --git a/Maths/WhileLoopFactorial.js b/Maths/WhileLoopFactorial.js
index 7e04bbafa..943fabd8d 100644
--- a/Maths/WhileLoopFactorial.js
+++ b/Maths/WhileLoopFactorial.js
@@ -1,15 +1,13 @@
 /*
-    author: Theepag
+    author: Theepag, optimised by merelymyself
  */
 export const factorialize = (num) => {
-  // Step 1. variable result to store num
-  let result = num
-  // If num = 0 OR 1, the factorial will return 1
-  if (num === 0 || num === 1) { return 1 }
+  // Step 1. Handles cases where num is 0 or 1, by returning 1.
+  let result = 1
   // Step 2. WHILE loop
   while (num > 1) {
+    result *= num // or result = result * num;
     num-- // decrement 1 at each iteration
-    result = result * num // or result = result * num;
   }
   // Step 3. Return the factorial
   return result
diff --git a/Maths/test/WhileLoopFactorial.test.js b/Maths/test/WhileLoopFactorial.test.js
new file mode 100644
index 000000000..6cec49f36
--- /dev/null
+++ b/Maths/test/WhileLoopFactorial.test.js
@@ -0,0 +1,12 @@
+import { factorialize } from '../WhileLoopFactorial'
+
+function testFactorial (n, expected) {
+  test('Testing on ' + n + '!', () => {
+    expect(factorialize(n)).toBe(expected)
+  })
+}
+
+testFactorial(3, 6)
+testFactorial(7, 5040)
+testFactorial(0, 1)
+testFactorial(12, 479001600)