bpo-35500: align expected and actual calls on mock.assert_called_with error message. (GH-11804)

1 files changed, 5 insertions, 2 deletions

diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index ef5c55d6a1..8f46050462 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -745,7 +745,7 @@ class NonCallableMock(Base):
 
 
     def _format_mock_failure_message(self, args, kwargs):
-        message = 'Expected call: %s\nActual call: %s'
+        message = 'expected call not found.\nExpected: %s\nActual: %s'
         expected_string = self._format_mock_call_signature(args, kwargs)
         call_args = self.call_args
         if len(call_args) == 3:
@@ -814,7 +814,10 @@ class NonCallableMock(Base):
         self = _mock_self
         if self.call_args is None:
             expected = self._format_mock_call_signature(args, kwargs)
-            raise AssertionError('Expected call: %s\nNot called' % (expected,))
+            actual = 'not called.'
+            error_message = ('expected call not found.\nExpected: %s\nActual: %s'
+                    % (expected, actual))
+            raise AssertionError(error_message)
 
         def _error_message():
             msg = self._format_mock_failure_message(args, kwargs)