fix: Enhance error handling in factorial function (TheAlgorithms#1430)

Author: yongeazi143

Recursive/Factorial.js

@@ -9,17 +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 (!Number.isInteger(n) || n < 0) {
+    throw new RangeError('Input should be a non-negative whole number')
   }
 
   if (n === 0) {
     return 1
   }
+
   return n * factorial(n - 1)
 }
 

Recursive/test/Factorial.test.js

@@ -10,10 +10,20 @@ describe('Factorial', () => {
   })
 
   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')
+    expect(() => factorial('-')).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(null)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(undefined)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(3.142)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(-1)).toThrow(
+      'Input should be a non-negative whole number'
+    )
   })
 })