diff --git a/tests/test_args.py b/tests/test_args.py
index 0f05df6d..80cc14d0 100644
--- a/tests/test_args.py
+++ b/tests/test_args.py
@@ -101,6 +101,11 @@ def test_failingParsing(self, mock_print) -> None:
       mock_print.mock_calls = []
       with patch.object(sys, "argv", ["alibuild"] + shlex.split(cmd)):
         self.assertRaises(FakeExit, doParseArgs)
+        if mock_print.mock_calls != calls:
+          import json
+          print('Failed test:', cmd)
+          print("Expected calls: ", json.dumps(calls, indent=2, default=str))
+          print("Actual calls: ", json.dumps(mock_print.mock_calls, indent=2, default=str))
         self.assertEqual(mock_print.mock_calls, calls)
 
   def test_validArchitectures(self) -> None: