Add unit tests with mocks for fetch_url function to simulate HTTP res…

…ponses and errors

tests/test_healthcheck.py

@@ -0,0 +1,46 @@
+"""Imports"""
+import unittest
+from unittest.mock import patch, MagicMock
+import requests
+from app.healthcheck import fetch_url
+
+
+class TestHealthCheck(unittest.TestCase):
+    """Unit Tests"""
+
+    @patch('app.healthcheck.requests.get')
+    @patch('app.healthcheck.sys.exit')
+    def test_fetch_url_success(self, mock_exit, mock_get):
+        """
+        Test fetch_url with a successful 200 status code
+        """
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_get.return_value = mock_response
+        fetch_url('http://localhost:5000')
+        mock_exit.assert_called_once_with(0)
+
+    @patch('app.healthcheck.requests.get')
+    @patch('app.healthcheck.sys.exit')
+    def test_fetch_url_non_200(self, mock_exit, mock_get):
+        """
+        Test fetch_url with a non-200 status code
+        """
+        mock_response = MagicMock()
+        mock_response.status_code = 500
+        mock_get.return_value = mock_response
+        fetch_url('http://localhost:5000')
+        mock_exit.assert_called_once_with(1)
+
+    @patch('app.healthcheck.requests.get', side_effect=requests.exceptions.Timeout)
+    @patch('app.healthcheck.sys.exit')
+    def test_fetch_url_timeout(self, mock_exit, _):
+        """
+        Test fetch_url handling of a timeout exception
+        """
+        fetch_url('http://localhost:5000')
+        mock_exit.assert_called_once_with(1)
+
+
+if __name__ == '__main__':
+    unittest.main()