fix: throw error and add tests for ReverseNumber (TheAlgorithms#1608)

Author: vil02

Maths/ReverseNumber.js

@@ -10,7 +10,7 @@
 const ReverseNumber = (number) => {
  // firstly, check that input is a number or not.
  if (typeof number !== 'number') {
- return new TypeError('Argument is not a number.')
+ throw new TypeError('Argument is not a number.')
  }
  // A variable for storing the reversed number.
  let reverseNumber = 0

Maths/test/ReverseNumber.test.js

@@ -0,0 +1,16 @@
+import { ReverseNumber } from '../ReverseNumber'
+
+describe('ReverseNumber', () => {
+ it.each([
+ [0, 0],
+ [10, 1],
+ [123, 321],
+ [100001, 100001]
+ ])('check with %j', (input, expected) => {
+ expect(expected).toEqual(ReverseNumber(input))
+ })
+
+ it('should throw when input is not a number', () => {
+ expect(() => ReverseNumber('100')).toThrowError()
+ })
+})