chore: check for invalid input to factorial (TheAlgorithms#1229)

Author: abdullyahuza

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
  }

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')
+ })
 })