Add original message from assert_* methods of the Mock object

Author: nicoddemus

CHANGELOG.rst

@@ -1,3 +1,15 @@
+1.6.0
+-----
+
+* The original assertions raised by the various ``Mock.assert_*`` methods
+  now appear in the failure message, in addition to the message obtained from
+  pytest introspection.
+  Thanks `@quodlibetor`_ for the initial patch (`#79`_).
+
+.. _@quodlibetor: https://github.com/quodlibetor
+
+.. _#79: https://github.com/pytest-dev/pytest-mock/pull/79
+
 1.5.0
 -----
 

README.rst

@@ -126,14 +126,30 @@ the method, and uses py.test's own `advanced assertions`_ to return a better
 diff::
 
 
-            m = mocker.patch.object(DS, 'create_char')
-            DS().create_char('Raistlin', class_='mag', gift=12)
-    >       m.assert_called_once_with('Raistlin', class_='mage', gift=12)
-    E       assert {'class_': 'mag', 'gift': 12} == {'class_': 'mage', 'gift': 12}
-    E         Omitting 1 identical items, use -v to show
-    E         Differing items:
-    E         {'class_': 'mag'} != {'class_': 'mage'}
+    mocker = <pytest_mock.MockFixture object at 0x0381E2D0>
+
+        def test(mocker):
+            m = mocker.Mock()
+            m('fo')
+    >       m.assert_called_once_with('', bar=4)
+    E       AssertionError: Expected call: mock('', bar=4)
+    E       Actual call: mock('fo')
+    E
+    E       pytest introspection follows:
+    E
+    E       Args:
+    E       assert ('fo',) == ('',)
+    E         At index 0 diff: 'fo' != ''
     E         Use -v to get the full diff
+    E       Kwargs:
+    E       assert {} == {'bar': 4}
+    E         Right contains more items:
+    E         {'bar': 4}
+    E         Use -v to get the full diff
+
+
+test_foo.py:6: AssertionError
+========================== 1 failed in 0.03 seconds ===========================
 
 
 This is useful when asserting mock calls with many/nested arguments and trying

pytest_mock.py

@@ -2,6 +2,7 @@
 import sys
 
 import pytest
+
 from _pytest_mock_version import version
 
 __version__ = version
@@ -172,18 +173,29 @@ def mock(mocker):
 
 def assert_wrapper(__wrapped_mock_method__, *args, **kwargs):
     __tracebackhide__ = True
-    err = None
     try:
         __wrapped_mock_method__(*args, **kwargs)
+        return
     except AssertionError as e:
-        __mock_self = args[0]
-        if __mock_self.call_args is not None:
-            actual_args, actual_kwargs = __mock_self.call_args
-            assert actual_args == args[1:]
-            assert actual_kwargs == kwargs
-        err = e
-    if err is not None:
-        raise AssertionError(*err.args)
+        if getattr(e, '_mock_introspection_applied', 0):
+            msg = str(e)
+        else:
+            __mock_self = args[0]
+            msg = str(e)
+            if __mock_self.call_args is not None:
+                actual_args, actual_kwargs = __mock_self.call_args
+                msg += '\n\npytest introspection follows:\n'
+                try:
+                    assert actual_args == args[1:]
+                except AssertionError as e:
+                    msg += '\nArgs:\n' + str(e)
+                try:
+                    assert actual_kwargs == kwargs
+                except AssertionError as e:
+                    msg += '\nKwargs:\n' + str(e)
+    e = AssertionError(msg)
+    e._mock_introspection_applied = True
+    raise e
 
 
 def wrap_assert_not_called(*args, **kwargs):

test_pytest_mock.py

@@ -4,7 +4,6 @@
 from contextlib import contextmanager
 
 import py.code
-
 import pytest
 
 pytest_plugins = 'pytester'
@@ -514,3 +513,29 @@ def runpytest_subprocess(testdir, *args):
     else:
         # pytest 2.7.X
         return testdir.runpytest(*args)
+
+
+def test_detailed_introspection(testdir):
+    """Check that the "mock_use_standalone" is being used.
+    """
+    testdir.makepyfile("""
+        def test(mocker):
+            m = mocker.Mock()
+            m('fo')
+            m.assert_called_once_with('', bar=4)
+    """)
+    result = testdir.runpytest('-s')
+    result.stdout.fnmatch_lines([
+        "*AssertionError: Expected call: mock('', bar=4)*",
+        "*Actual call: mock('fo')*",
+        "*pytest introspection follows:*",
+        '*Args:',
+        "*assert ('fo',) == ('',)",
+        "*At index 0 diff: 'fo' != ''*",
+        "*Use -v to get the full diff*",
+        "*Kwargs:*",
+        "*assert {} == {'bar': 4}*",
+        "*Right contains more items:*",
+        "*{'bar': 4}*",
+        "*Use -v to get the full diff*",
+    ])