From 6f91ba2275960f6bd197c7946860e0224175b0a7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C4=9Bj=20Chalk?= <matej.chalk@flowup.cz>
Date: Mon, 17 Jun 2024 14:32:59 +0200
Subject: [PATCH] fix: throw if average called with empty array

---
 src/index.js       | 3 +++
 test/index.test.js | 7 +++++++
 2 files changed, 10 insertions(+)

diff --git a/src/index.js b/src/index.js
index d2f047e..30d8f45 100644
--- a/src/index.js
+++ b/src/index.js
@@ -13,6 +13,9 @@ export function sum(values) {
  * @returns {number} Average of all numbers.
  */
 export function average(values) {
+  if (values.length === 0) {
+    throw new Error('Cannot calculate average from empty array');
+  }
   return sum(values) / values.length;
 }
 
diff --git a/test/index.test.js b/test/index.test.js
index 3eea261..97078cf 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -16,6 +16,13 @@ describe('average', () => {
   it('should calculate average', () => {
     assert.strictEqual(average([1, 2, 3, 4]), 2.5);
   });
+
+  it('should throw for empty array', () => {
+    assert.throws(
+      () => average([]),
+      'Cannot calculate average for empty array'
+    );
+  });
 });
 
 describe('sort', () => {