From 5364a1c31be7d787a10a9fa0ed287844ff35c618 Mon Sep 17 00:00:00 2001
From: Abdulrazak Yahuza <40579655+abdullyahuza@users.noreply.github.com>
Date: Thu, 27 Oct 2022 19:45:53 +0100
Subject: [PATCH] chore: check for invalid input to factorial (#1229)

---
 Recursive/Factorial.js           | 8 ++++++++
 Recursive/test/Factorial.test.js | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/Recursive/Factorial.js b/Recursive/Factorial.js
index 5d882e5ea..5a0d56051 100644
--- a/Recursive/Factorial.js
+++ b/Recursive/Factorial.js
@@ -9,6 +9,14 @@
  */
 
 const factorial = (n) => {
+  if (!Number.isInteger(n)) {
+    throw new RangeError('Not a Whole Number')
+  }
+
+  if (n < 0) {
+    throw new RangeError('Not a Positive Number')
+  }
+
   if (n === 0) {
     return 1
   }
diff --git a/Recursive/test/Factorial.test.js b/Recursive/test/Factorial.test.js
index b124efea5..5f32a4433 100644
--- a/Recursive/test/Factorial.test.js
+++ b/Recursive/test/Factorial.test.js
@@ -8,4 +8,12 @@ describe('Factorial', () => {
   it('should return factorial 120 for value "5"', () => {
     expect(factorial(5)).toBe(120)
   })
+
+  it('Throw Error for Invalid Input', () => {
+    expect(() => factorial('-')).toThrow('Not a Whole Number')
+    expect(() => factorial(null)).toThrow('Not a Whole Number')
+    expect(() => factorial(undefined)).toThrow('Not a Whole Number')
+    expect(() => factorial(3.142)).toThrow('Not a Whole Number')
+    expect(() => factorial(-1)).toThrow('Not a Positive Number')
+  })
 })