Test failure with Python 3.12

[fabaff]

There is a failure with Python 3.12. The test passes on Python < 3.12.

============================= test session starts ==============================
platform linux -- Python 3.12.1, pytest-7.4.3, pluggy-1.3.0
rootdir: /build/source
collected 59 items                                                             

test/test_filereader.py .                                                [  1%]
[...]
test/test_parse_v5_eon_hungary.py ....                                   [ 54%]
test/test_protocol.py .F                                                 [ 57%]
test/test_rfxtrx_protocol.py .                                           [ 59%]
test/test_telegram_buffer.py .........                                   [ 74%]
test/objects/test_mbusdevice.py ...                                      [ 79%]
test/objects/test_parser_corner_cases.py ....                            [ 86%]
test/objects/test_telegram.py ........                                   [100%]

=================================== FAILURES ===================================
_______________________ ProtocolTest.test_receive_packet _______________________

self = <test.test_protocol.ProtocolTest testMethod=test_receive_packet>

    def test_receive_packet(self):
        """Protocol packet reception."""
    
        mock_transport = Mock()
        self.protocol.connection_made(mock_transport)
        assert not self.protocol._active
    
        self.protocol.data_received(TELEGRAM_V2_2.encode('ascii'))
        assert self.protocol._active
    
        # 1st call of keep_alive resets 'active' flag
        self.protocol.keep_alive()
        assert not self.protocol._active
    
        # 2nd call of keep_alive should close the transport
        self.protocol.keep_alive()
>       assert mock_transport.close.called_once()

test/test_protocol.py:71: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <Mock name='mock.close' id='140737310204912'>, name = 'called_once'

    def __getattr__(self, name):
        if name in {'_mock_methods', '_mock_unsafe'}:
            raise AttributeError(name)
        elif self._mock_methods is not None:
            if name not in self._mock_methods or name in _all_magics:
                raise AttributeError("Mock object has no attribute %r" % name)
        elif _is_magic(name):
            raise AttributeError(name)
        if not self._mock_unsafe and (not self._mock_methods or name not in self._mock_methods):
            if name.startswith(('assert', 'assret', 'asert', 'aseert', 'assrt')) or name in _ATTRIB_DENY_LIST:
>               raise AttributeError(
                    f"{name!r} is not a valid assertion. Use a spec "
                    f"for the mock if {name!r} is meant to be an attribute.")
E               AttributeError: 'called_once' is not a valid assertion. Use a spec for the mock if 'called_once' is meant to be an attribute.

/nix/store/r2pbmhh7l7g6f3avk8vg8d33frl4c2sx-python3-3.12.1/lib/python3.12/unittest/mock.py:663: AttributeError
------------------------------ Captured log call -------------------------------
WARNING  dsmr_parser.clients.protocol:protocol.py:142 keep-alive check failed
=============================== warnings summary ===============================
../../nix/store/jl22rhi9ch8qci1ssjvwrfw9asajbbpa-python3.12-python-dateutil-2.8.2/lib/python3.12/site-packages/dateutil/tz/tz.py:37
  /nix/store/jl22rhi9ch8qci1ssjvwrfw9asajbbpa-python3.12-python-dateutil-2.8.2/lib/python3.12/site-packages/dateutil/tz/tz.py:37: DeprecationWarning: datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.fromtimestamp(timestamp, datetime.UTC).
    EPOCH = datetime.datetime.utcfromtimestamp(0)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED test/test_protocol.py::ProtocolTest::test_receive_packet - AttributeError: 'called_once' is not a valid assertion. Use a spec for the ...
=================== 1 failed, 58 passed, 1 warning in 0.60s ====================
/nix/store/v5irq7wvkr7kih0hhnch5nnv2dcq8c4f-stdenv-linux/setup: line 1557: pop_var_context: head of shell_variables not a function context
error: builder for '/nix/store/wzafawdgiz41173yrw48a6kkpz3pcdd0-python3.12-dsmr-parser-1.3.1.drv' failed with exit code 1;
       last 10 log lines:
       > =============================== warnings summary ===============================
       > ../../nix/store/jl22rhi9ch8qci1ssjvwrfw9asajbbpa-python3.12-python-dateutil-2.8.2/lib/python3.12/site-packages/dateutil/tz/tz.py:37
       >   /nix/store/jl22rhi9ch8qci1ssjvwrfw9asajbbpa-python3.12-python-dateutil-2.8.2/lib/python3.12/site-packages/dateutil/tz/tz.py:37: DeprecationWarning: datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.datetime.fromtimestamp(timestamp, datetime.UTC).
       >     EPOCH = datetime.datetime.utcfromtimestamp(0)
       >
       > -- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
       > =========================== short test summary info ============================
       > FAILED test/test_protocol.py::ProtocolTest::test_receive_packet - AttributeError: 'called_once' is not a valid assertion. Use a spec for the ...
       > =================== 1 failed, 58 passed, 1 warning in 0.60s ====================

[ndokter]

Thanks for creating the issue. I have made a fix and released it as v1.3.2