🛡️ Sentinel: [MEDIUM] Fix test suite SSRF mock bypass

Added explicit mock assertions (`assert_called_once()`) to `test_is_reachable_failure` and `test_is_reachable_success` to prevent false positive test passes. Updated test IP to a globally routable address (`8.8.4.4`) to bypass SSRF logic correctly so that failure simulation path can be executed.

Co-authored-by: ManupaKDU <95234271+ManupaKDU@users.noreply.github.com>

Author: google-labs-jules[bot]

test_testping1.py

@@ -12,14 +12,17 @@ def test_is_reachable_success(self, mock_call):
         mock_call.return_value = 0
 
         self.assertTrue(is_reachable('8.8.8.8'))
+        mock_call.assert_called_once()
 
     @patch('testping1.subprocess.call')
     def test_is_reachable_failure(self, mock_call):
         """Test is_reachable returns False for a failed ping."""
         # Simulate a failed ping response by returning a non-zero exit code
         mock_call.return_value = 1
 
-        self.assertFalse(is_reachable('10.0.0.1'))
+        # 🛡️ Sentinel: Use a public IP to ensure SSRF blocklist doesn't bypass network logic test
+        self.assertFalse(is_reachable('8.8.4.4'))
+        mock_call.assert_called_once()
 
     @patch('testping1.subprocess.call')
     def test_is_reachable_invalid_ip_format(self, mock_call):