Better error message when dealing with functional tests fail

1 files changed, 10 insertions, 4 deletions

diff --git a/pylint/testutils/lint_module_test.py b/pylint/testutils/lint_module_test.py
index 786e1bec5..653a6dcdb 100644
--- a/pylint/testutils/lint_module_test.py
+++ b/pylint/testutils/lint_module_test.py
@@ -7,7 +7,7 @@ import platform
 import sys
 from collections import Counter
 from io import StringIO
-from typing import Dict, Tuple
+from typing import Dict, List, Tuple
 
 import pytest
 
@@ -168,10 +168,14 @@ class LintModuleTest:
         actual_messages, actual_output = self._get_actual()
         assert (
             expected_messages == actual_messages
-        ), self.error_msg_for_unequal_messages(actual_messages, expected_messages)
+        ), self.error_msg_for_unequal_messages(
+            actual_messages, expected_messages, actual_output
+        )
         self._check_output_text(expected_messages, expected_output, actual_output)
 
-    def error_msg_for_unequal_messages(self, actual_messages, expected_messages):
+    def error_msg_for_unequal_messages(
+        self, actual_messages, expected_messages, actual_output: List[OutputLine]
+    ):
         msg = ['Wrong results for file "%s":' % (self._test_file.base)]
         missing, unexpected = self.multiset_difference(
             expected_messages, actual_messages
@@ -181,8 +185,10 @@ class LintModuleTest:
             msg.extend(" %3d: %s" % msg for msg in sorted(missing))
         if unexpected:
             msg.append("\nUnexpected in testdata:")
-            msg.extend(" %3d: %s" % msg for msg in sorted(unexpected))
+            msg.extend(" %3d: %s" % msg for msg in sorted(unexpected))  # type: ignore
         error_msg = "\n".join(msg)
+        error_msg += "\n\nActual pylint output for this file:\n"
+        error_msg += "\n".join(str(o) for o in actual_output)
         return error_msg
 
     def error_msg_for_unequal_output(self, expected_lines, received_lines) -> str: