tests/test_connection.py::test_constant_packet_size PASSED               [100%]
tests/test_connection.py::test_constant_packet_size ERROR                [100%]

==================================== ERRORS ====================================
________________ ERROR at teardown of test_constant_packet_size ________________

have_pcap_tools = None
tmp_path = PosixPath('/tmp/pytest-of-rusty/pytest-0/test_constant_packet_size0')

    @pytest.fixture
    def tcp_capture(have_pcap_tools, tmp_path):
        # You will need permissions.  Most distributions have a group which has
        # permissions to use dumpcap:
        #     $ ls -l /usr/bin/dumpcap
        #     -rwxr-xr-- 1 root wireshark 229112 Apr 16  2024 /usr/bin/dumpcap
        #     $ getcap /usr/bin/dumpcap
        #     /usr/bin/dumpcap cap_net_admin,cap_net_raw=eip
        # So you just need to be in the wireshark group.
        cap = TcpCapture(tmp_path)
        yield cap
        cap.stop()
>       cap.assert_constant_payload()

tests/fixtures.py:193: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <fixtures.TcpCapture object at 0x731d573af230>

    def assert_constant_payload(self):
        tshark_cmd = [
            "tshark",
            "-r", str(self.pcap),
            "-Y", "tcp.len > 0",
            "-T", "fields",
            "-e", "tcp.len",
        ]
    
        out = subprocess.check_output(tshark_cmd, text=True)
        lengths = [int(x) for x in out.splitlines() if x.strip()]
    
        assert lengths, f"No TCP payload packets captured on port {self.port}"
    
        uniq = set(lengths)
>       assert len(uniq) == 1, (
               ^^^^^^^^^^^^^^