Make base URL configurable using HELPFUL_TOOLS_BASE_URL environment variable in tests

Author: susamn

tests/text-diff/test_text_diff_frontend.py

@@ -34,7 +34,7 @@ def setUpClass(cls):
             # Fallback to Firefox if Chrome not available
             cls.driver = webdriver.Firefox()
 
-        cls.base_url = "http://localhost:8000"  # Adjust port as needed
+        cls.base_url = os.environ.get('HELPFUL_TOOLS_BASE_URL', "http://localhost:8000")
         cls.wait = WebDriverWait(cls.driver, 10)
 
     @classmethod