Upgrading to 1.10.2 does NOT help.

Fixed upstream in 1.10.3

https://github.com/pytest-dev/pytest-mock/pull/140

https://src.fedoraproject.org/rpms/python-pytest-mock/pull-request/1

1.10.4 fails again: https://copr.fedorainfracloud.org/coprs/g/python/python3.8/build/971242/

Are you sure? From your link, it seems it worked.

That link shows "failed". I've tried again to be sure: https://copr.fedorainfracloud.org/coprs/g/python/python3.8/build/971268/ again "failed"

The failure is on Python 2 however (weird):

+ py.test-2.7 test_pytest_mock.py
============================= test session starts ==============================
platform linux2 -- Python 2.7.16, pytest-4.4.1, py-1.8.0, pluggy-0.11.0
rootdir: /builddir/build/BUILD/pytest-mock-1.10.4, inifile: tox.ini
plugins: mock-1.10.4
collected 50 items

test_pytest_mock.py ...................FFFFF....x..x..............sF..   [100%]

=================================== FAILURES ===================================
_______________ TestMockerStub.test_failure_message_with_no_name _______________

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d249e0>
mocker = <pytest_mock.MockFixture object at 0x7f3916e9ced0>

    def test_failure_message_with_no_name(self, mocker):
>       self.__test_failure_message(mocker)

test_pytest_mock.py:223: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d249e0>
mocker = <pytest_mock.MockFixture object at 0x7f3916e9ced0>, kwargs = {}
expected_name = 'mock', msg = 'Expected call: {0}()\nNot called'
expected_message = 'Expected call: mock()\nNot called'
stub = <MagicMock spec='function' id='139883174282960'>
exc_info = <ExceptionInfo AssertionError tblen=3>
@py_assert2 = AssertionError(u'expected call not found.\nExpected: mock()\nActual: not called.',)
@py_assert4 = 'expected call not found.\nExpected: mock()\nActual: not called.'

    def __test_failure_message(self, mocker, **kwargs):
        expected_name = kwargs.get("name") or "mock"
        if PY38:
            msg = "expected call not found.\nExpected: {0}()\nActual: not called."
        else:
            msg = "Expected call: {0}()\nNot called"
        expected_message = msg.format(expected_name)
        stub = mocker.stub(**kwargs)
        with pytest.raises(AssertionError) as exc_info:
            stub.assert_called_with()
>       assert str(exc_info.value) == expected_message
E       AssertionError: assert 'expected cal...: not called.' == 'Expected call...)\nNot called'
E         - expected call not found.
E         - Expected: mock()
E         + Expected call: mock()
E         ?         +++++
E         - Actual: not called.
E         + Not called

test_pytest_mock.py:220: AssertionError
_____________ TestMockerStub.test_failure_message_with_name[None] ______________

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916eaa638>
mocker = <pytest_mock.MockFixture object at 0x7f3916d17e50>, name = None

    @pytest.mark.parametrize("name", (None, "", "f", "The Castle of aaarrrrggh"))
    def test_failure_message_with_name(self, mocker, name):
>       self.__test_failure_message(mocker, name=name)

test_pytest_mock.py:227: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916eaa638>
mocker = <pytest_mock.MockFixture object at 0x7f3916d17e50>
kwargs = {'name': None}, expected_name = 'mock'
msg = 'Expected call: {0}()\nNot called'
expected_message = 'Expected call: mock()\nNot called'
stub = <MagicMock spec='function' id='139883172691024'>
exc_info = <ExceptionInfo AssertionError tblen=3>
@py_assert2 = AssertionError(u'expected call not found.\nExpected: mock()\nActual: not called.',)
@py_assert4 = 'expected call not found.\nExpected: mock()\nActual: not called.'

    def __test_failure_message(self, mocker, **kwargs):
        expected_name = kwargs.get("name") or "mock"
        if PY38:
            msg = "expected call not found.\nExpected: {0}()\nActual: not called."
        else:
            msg = "Expected call: {0}()\nNot called"
        expected_message = msg.format(expected_name)
        stub = mocker.stub(**kwargs)
        with pytest.raises(AssertionError) as exc_info:
            stub.assert_called_with()
>       assert str(exc_info.value) == expected_message
E       AssertionError: assert 'expected cal...: not called.' == 'Expected call...)\nNot called'
E         - expected call not found.
E         - Expected: mock()
E         + Expected call: mock()
E         ?         +++++
E         - Actual: not called.
E         + Not called

test_pytest_mock.py:220: AssertionError
_______________ TestMockerStub.test_failure_message_with_name[] ________________

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d8b9e0>
mocker = <pytest_mock.MockFixture object at 0x7f3916d87410>, name = ''

    @pytest.mark.parametrize("name", (None, "", "f", "The Castle of aaarrrrggh"))
    def test_failure_message_with_name(self, mocker, name):
>       self.__test_failure_message(mocker, name=name)

test_pytest_mock.py:227: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d8b9e0>
mocker = <pytest_mock.MockFixture object at 0x7f3916d87410>
kwargs = {'name': ''}, expected_name = 'mock'
msg = 'Expected call: {0}()\nNot called'
expected_message = 'Expected call: mock()\nNot called'
stub = <MagicMock spec='function' id='139883173148304'>
exc_info = <ExceptionInfo AssertionError tblen=3>
@py_assert2 = AssertionError(u'expected call not found.\nExpected: mock()\nActual: not called.',)
@py_assert4 = 'expected call not found.\nExpected: mock()\nActual: not called.'

    def __test_failure_message(self, mocker, **kwargs):
        expected_name = kwargs.get("name") or "mock"
        if PY38:
            msg = "expected call not found.\nExpected: {0}()\nActual: not called."
        else:
            msg = "Expected call: {0}()\nNot called"
        expected_message = msg.format(expected_name)
        stub = mocker.stub(**kwargs)
        with pytest.raises(AssertionError) as exc_info:
            stub.assert_called_with()
>       assert str(exc_info.value) == expected_message
E       AssertionError: assert 'expected cal...: not called.' == 'Expected call...)\nNot called'
E         - expected call not found.
E         - Expected: mock()
E         + Expected call: mock()
E         ?         +++++
E         - Actual: not called.
E         + Not called

test_pytest_mock.py:220: AssertionError
_______________ TestMockerStub.test_failure_message_with_name[f] _______________

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916df9488>
mocker = <pytest_mock.MockFixture object at 0x7f3916d9b3d0>, name = 'f'

    @pytest.mark.parametrize("name", (None, "", "f", "The Castle of aaarrrrggh"))
    def test_failure_message_with_name(self, mocker, name):
>       self.__test_failure_message(mocker, name=name)

test_pytest_mock.py:227: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916df9488>
mocker = <pytest_mock.MockFixture object at 0x7f3916d9b3d0>
kwargs = {'name': 'f'}, expected_name = 'f'
msg = 'Expected call: {0}()\nNot called'
expected_message = 'Expected call: f()\nNot called'
stub = <MagicMock name='f' spec='function' id='139883173230992'>
exc_info = <ExceptionInfo AssertionError tblen=3>
@py_assert2 = AssertionError(u'expected call not found.\nExpected: f()\nActual: not called.',)
@py_assert4 = 'expected call not found.\nExpected: f()\nActual: not called.'

    def __test_failure_message(self, mocker, **kwargs):
        expected_name = kwargs.get("name") or "mock"
        if PY38:
            msg = "expected call not found.\nExpected: {0}()\nActual: not called."
        else:
            msg = "Expected call: {0}()\nNot called"
        expected_message = msg.format(expected_name)
        stub = mocker.stub(**kwargs)
        with pytest.raises(AssertionError) as exc_info:
            stub.assert_called_with()
>       assert str(exc_info.value) == expected_message
E       AssertionError: assert 'expected cal...: not called.' == 'Expected call...)\nNot called'
E         - expected call not found.
E         - Expected: f()
E         + Expected call: f()
E         ?         +++++
E         - Actual: not called.
E         + Not called

test_pytest_mock.py:220: AssertionError
___ TestMockerStub.test_failure_message_with_name[The Castle of aaarrrrggh] ____

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d29b48>
mocker = <pytest_mock.MockFixture object at 0x7f3916efc4d0>
name = 'The Castle of aaarrrrggh'

    @pytest.mark.parametrize("name", (None, "", "f", "The Castle of aaarrrrggh"))
    def test_failure_message_with_name(self, mocker, name):
>       self.__test_failure_message(mocker, name=name)

test_pytest_mock.py:227: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <test_pytest_mock.TestMockerStub instance at 0x7f3916d29b48>
mocker = <pytest_mock.MockFixture object at 0x7f3916efc4d0>
kwargs = {'name': 'The Castle of aaarrrrggh'}
expected_name = 'The Castle of aaarrrrggh'
msg = 'Expected call: {0}()\nNot called'
expected_message = 'Expected call: The Castle of aaarrrrggh()\nNot called'
stub = <MagicMock name='The Castle of aaarrrrggh' spec='function' id='139883174676176'>
exc_info = <ExceptionInfo AssertionError tblen=3>
@py_assert2 = AssertionError(u'expected call not found.\nExpected: The Castle of aaarrrrggh()\nActual: not called.',)
@py_assert4 = 'expected call not found.\nExpected: The Castle of aaarrrrggh()\nActual: not called.'

    def __test_failure_message(self, mocker, **kwargs):
        expected_name = kwargs.get("name") or "mock"
        if PY38:
            msg = "expected call not found.\nExpected: {0}()\nActual: not called."
        else:
            msg = "Expected call: {0}()\nNot called"
        expected_message = msg.format(expected_name)
        stub = mocker.stub(**kwargs)
        with pytest.raises(AssertionError) as exc_info:
            stub.assert_called_with()
>       assert str(exc_info.value) == expected_message
E       AssertionError: assert 'expected cal...: not called.' == 'Expected call...)\nNot called'
E         - expected call not found.
E         - Expected: The Castle of aaarrrrggh()
E         + Expected call: The Castle of aaarrrrggh()
E         ?         +++++
E         - Actual: not called.
E         + Not called

test_pytest_mock.py:220: AssertionError
_________________________ test_detailed_introspection __________________________

testdir = <Testdir local('/tmp/pytest-of-mockbuild/pytest-0/test_detailed_introspection0')>

    @pytest.mark.usefixtures("needs_assert_rewrite")
    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")
        if PY38:
            expected_lines = [
                "*AssertionError: expected call not found.",
                "*Expected: mock('', bar=4)",
                "*Actual: mock('fo')",
            ]
        else:
            expected_lines = [
                "*AssertionError: Expected call: mock('', bar=4)*",
                "*Actual call: mock('fo')*",
            ]
        expected_lines += [
            "*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*",
        ]
>       result.stdout.fnmatch_lines(expected_lines)
E       Failed: nomatch: "*AssertionError: Expected call: mock('', bar=4)*"
E           and: u'============================= test session starts =============================='
E           and: u'platform linux2 -- Python 2.7.16, pytest-4.4.1, py-1.8.0, pluggy-0.11.0'
E           and: u'rootdir: /tmp/pytest-of-mockbuild/pytest-0/test_detailed_introspection0'
E           and: u'plugins: mock-1.10.4'
E           and: u'collected 1 item'
E           and: u''
E           and: u'test_detailed_introspection.py F'
E           and: u''
E           and: u'=================================== FAILURES ==================================='
E           and: u'_____________________________________ test _____________________________________'
E           anderror: Bad exit status from /var/tmp/rpm-tmp.OTjS7u (%check)
: u''
E           and: u'mocker = <pytest_mock.MockFixture object at 0x7f3916dde050>'
E           and: u''
E           and: u'    def test(mocker):'
E           and: u'        m = mocker.Mock()'
E           and: u"        m('fo')"
E           and: u">       m.assert_called_once_with('', bar=4)"
E           and: u'E       AssertionError: expected call not found.'
E           and: u"E       Expected: mock('', bar=4)"
E           and: u"E       Actual: mock('fo')"
E           and: u'E       '
E           and: u'E       pytest introspection follows:'
E           and: u'E       '
E           and: u'E       Args:'
E           and: u"E       assert ('fo',) == ('',)"
E           and: u"E         At index 0 diff: 'fo' != ''"
E           and: u'E         Use -v to get the full diff'
E           and: u'E       Kwargs:'
E           and: u"E       assert {} == {'bar': 4}"
E           and: u'E         Right contains more items:'
E           and: u"E         {'bar': 4}"
E           and: u'E         Use -v to get the full diff'
E           and: u''
E           and: u'test_detailed_introspection.py:4: AssertionError'
E           and: u'=========================== 1 failed in 0.01 seconds ==========================='
E           and: u''
E       remains unmatched: "*AssertionError: Expected call: mock('', bar=4)*"

/builddir/build/BUILD/pytest-mock-1.10.4/test_pytest_mock.py:646: Failed
----------------------------- Captured stdout call -----------------------------
============================= test session starts ==============================
platform linux2 -- Python 2.7.16, pytest-4.4.1, py-1.8.0, pluggy-0.11.0
rootdir: /tmp/pytest-of-mockbuild/pytest-0/test_detailed_introspection0
plugins: mock-1.10.4
collected 1 item

test_detailed_introspection.py F

=================================== FAILURES ===================================
_____________________________________ test _____________________________________

mocker = <pytest_mock.MockFixture object at 0x7f3916dde050>

    def test(mocker):
        m = mocker.Mock()
        m('fo')
>       m.assert_called_once_with('', bar=4)
E       AssertionError: expected call not found.
E       Expected: mock('', bar=4)
E       Actual: 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_detailed_introspection.py:4: AssertionError
=========================== 1 failed in 0.01 seconds ===========================
=========================== short test summary info ============================
SKIPPED [1] test_pytest_mock.py:580: Py3 only
XFAIL test_pytest_mock.py::test_class_method_subclass_spy
  does not work on Python 2
XFAIL test_pytest_mock.py::test_static_method_subclass_spy
  does not work on Python 2
FAILED test_pytest_mock.py::TestMockerStub::test_failure_message_with_no_name
FAILED test_pytest_mock.py::TestMockerStub::test_failure_message_with_name[None]
FAILED test_pytest_mock.py::TestMockerStub::test_failure_message_with_name[]
FAILED test_pytest_mock.py::TestMockerStub::test_failure_message_with_name[f]
FAILED test_pytest_mock.py::TestMockerStub::test_failure_message_with_name[The Castle of aaarrrrggh]
FAILED test_pytest_mock.py::test_detailed_introspection
========== 6 failed, 41 passed, 1 skipped, 2 xfailed in 2.17 seconds ===========

*** This bug has been marked as a duplicate of bug 1732702 ***