From f5e4733e1f599116c858417cc19df55e44b6b58d Mon Sep 17 00:00:00 2001
From: "eugene.yurchenko" <jackyurchenco@gmail.com>
Date: Wed, 4 Feb 2026 22:54:56 +0200
Subject: [PATCH] test: add edge case for factorial (negative)

---
 src/algorithms/math/factorial/__test__/factorial.test.js | 4 ++++
 src/algorithms/math/factorial/factorial.js               | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/src/algorithms/math/factorial/__test__/factorial.test.js b/src/algorithms/math/factorial/__test__/factorial.test.js
index bf6aa0ecbd..cee9e6b5f1 100644
--- a/src/algorithms/math/factorial/__test__/factorial.test.js
+++ b/src/algorithms/math/factorial/__test__/factorial.test.js
@@ -8,4 +8,8 @@ describe('factorial', () => {
     expect(factorial(8)).toBe(40320);
     expect(factorial(10)).toBe(3628800);
   });
+
+  it('factorial of negative should throw', () => {
+    expect(() => factorial(-1)).toThrow();
+  });
 });
diff --git a/src/algorithms/math/factorial/factorial.js b/src/algorithms/math/factorial/factorial.js
index 6c717d051f..9730d4f4f5 100644
--- a/src/algorithms/math/factorial/factorial.js
+++ b/src/algorithms/math/factorial/factorial.js
@@ -3,6 +3,9 @@
  * @return {number}
  */
 export default function factorial(number) {
+  if (number < 0) {
+    throw new RangeError('Number must be greater than 0');
+  }
   let result = 1;
 
   for (let i = 2; i <= number; i += 1) {