From d192a207dd93326ab2a1fe5f35b13a066ad5140b Mon Sep 17 00:00:00 2001
From: hurali97 <hurali97@gmail.com>
Date: Mon, 2 Sep 2024 13:49:59 +0500
Subject: [PATCH 1/3] fix: add explicity check for typeof string to prevent
 undefined behaviour later

---
 lib/str.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/str.ts b/lib/str.ts
index 4ec80683..23bb2ae5 100644
--- a/lib/str.ts
+++ b/lib/str.ts
@@ -994,6 +994,7 @@ const Str = {
      * without query parameters
      */
     getExtension(url: string): string | undefined {
+        if (typeof url !== 'string') return undefined;
         return url.split('.').pop()?.split('?')[0]?.toLowerCase();
     },
 

From 94b31d32c580a01937c1ac903a2fb79eeba86609 Mon Sep 17 00:00:00 2001
From: hurali97 <hurali97@gmail.com>
Date: Mon, 2 Sep 2024 13:50:26 +0500
Subject: [PATCH 2/3] test: add test cases for handling undefined behaviour of
 getExtension function

---
 __tests__/Str-test.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/__tests__/Str-test.js b/__tests__/Str-test.js
index b667118c..e91c0d5c 100644
--- a/__tests__/Str-test.js
+++ b/__tests__/Str-test.js
@@ -215,3 +215,19 @@ describe('Str.isValidE164Phone', () => {
         expect(Str.isValidE164Phone('+14404589784')).toBeTruthy();
     });
 });
+
+describe('Str.getExtension', () => {
+    it('Correctly returns extension', () => {
+        expect(Str.getExtension(buildTestURLForType('pdf'))).toBeTruthy();
+        expect(Str.getExtension(buildTestURLForType('PDF'))).toBeTruthy();
+        expect(Str.getExtension(buildTestURLForType('mov'))).toBeTruthy();
+        expect(Str.getExtension(buildTestURLForType('MP4'))).toBeTruthy();
+    });
+
+    it('Returns undefined for data types other than string', () => {
+        expect(Str.getExtension(0)).toBeUndefined();
+        expect(Str.getExtension(null)).toBeUndefined();
+        expect(Str.getExtension(undefined)).toBeUndefined();
+        expect(Str.getExtension([])).toBeUndefined();
+    });
+});
\ No newline at end of file

From 01a05043dd550170d8c3a6d59daa8482270fcbf9 Mon Sep 17 00:00:00 2001
From: hurali97 <hurali97@gmail.com>
Date: Tue, 10 Sep 2024 12:02:24 +0500
Subject: [PATCH 3/3] feat: add Log.warn in case of type mis match

---
 lib/str.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/str.ts b/lib/str.ts
index 23bb2ae5..2c367730 100644
--- a/lib/str.ts
+++ b/lib/str.ts
@@ -6,6 +6,7 @@ import * as HtmlEntities from 'html-entities';
 import * as Constants from './CONST';
 import * as UrlPatterns from './Url';
 import * as Utils from './utils';
+import Log from './Log';
 
 const REMOVE_SMS_DOMAIN_PATTERN = /@expensify\.sms/gi;
 
@@ -994,7 +995,10 @@ const Str = {
      * without query parameters
      */
     getExtension(url: string): string | undefined {
-        if (typeof url !== 'string') return undefined;
+        if (typeof url !== 'string') {
+            Log.warn('Str.getExtension: url is not a string', {url});
+            return undefined;
+        }
         return url.split('.').pop()?.split('?')[0]?.toLowerCase();
     },