jupyter-client v6.1.13 breaks qtconsole

[carlosperate]

I've reported this in the jupyter-client repository as well, as it looks like a breaking change in a patch release (not sure if the project using semver though). This might be a wrong assumption, so it's worth reporting here as well for visibility: jupyter/jupyter_client#635

Can be replicated using the latest qtconsole 5.0.3, which by default installs the latest jupyter-client:

$ pip install qtconsole PyQt5
...

$ pip list
Package          Version
---------------- -------
appnope          0.1.2
backcall         0.2.0
decorator        5.0.5
ipykernel        5.5.3
ipython          7.16.1
ipython-genutils 0.2.0
jedi             0.18.0
jupyter-client   6.1.13
jupyter-core     4.7.1
nest-asyncio     1.5.1
parso            0.8.2
pexpect          4.8.0
pickleshare      0.7.5
pip              21.0.1
prompt-toolkit   3.0.18
ptyprocess       0.7.0
Pygments         2.8.1
PyQt5            5.15.4
PyQt5-Qt5        5.15.2
PyQt5-sip        12.8.1
python-dateutil  2.8.1
pyzmq            22.0.3
qtconsole        5.0.3
QtPy             1.9.0
setuptools       54.2.0
six              1.15.0
tornado          6.1
traitlets        4.3.3
wcwidth          0.2.5
wheel            0.36.2

$ jupyter qtconsole
Traceback (most recent call last):
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/bin/jupyter-qtconsole", line 8, in <module>
    sys.exit(main())
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/qtconsole/qtconsoleapp.py", line 462, in main
    JupyterQtConsoleApp.launch_instance()
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_core/application.py", line 254, in launch_instance
    return super(JupyterApp, cls).launch_instance(argv=argv, **kwargs)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/traitlets/config/application.py", line 663, in launch_instance
    app.initialize(argv)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/decorator.py", line 232, in fun
    return caller(func, *(extras + args), **kw)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/traitlets/config/application.py", line 87, in catch_config_error
    return method(app, *args, **kwargs)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/qtconsole/qtconsoleapp.py", line 432, in initialize
    JupyterConsoleApp.initialize(self,argv)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_client/consoleapp.py", line 366, in initialize
    self.init_kernel_client()
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_client/consoleapp.py", line 354, in init_kernel_client
    self.kernel_client.start_channels()
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/qtconsole/kernel_mixins.py", line 47, in start_channels
    super().start_channels(*args, **kw)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_client/threaded.py", line 248, in start_channels
    super().start_channels(shell, iopub, stdin, hb, control)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_client/client.py", line 295, in start_channels
    self.hb_channel.start()
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/jupyter_client/client.py", line 364, in hb_channel
    self._hb_channel = self.hb_channel_class(self.context, self.session, url)
  File "/Users/microbit-carlos/workspace/deleteme/really-delete/qtconsole/.venv/lib/python3.6/site-packages/qtconsole/util.py", line 64, in __new__
    QClass.__init__(inst)
TypeError: __init__() missing 1 required positional argument: 'context'

Reverting to 6.1.12 and it all works:

$ pip install jupyter-client==6.1.12
Collecting jupyter-client==6.1.12
  Using cached jupyter_client-6.1.12-py3-none-any.whl (112 kB)
Requirement already satisfied: tornado>=4.1 in ./.venv/lib/python3.6/site-packages (from jupyter-client==6.1.12) (6.1)
Requirement already satisfied: jupyter-core>=4.6.0 in ./.venv/lib/python3.6/site-packages (from jupyter-client==6.1.12) (4.7.1)
Requirement already satisfied: python-dateutil>=2.1 in ./.venv/lib/python3.6/site-packages (from jupyter-client==6.1.12) (2.8.1)
Requirement already satisfied: traitlets in ./.venv/lib/python3.6/site-packages (from jupyter-client==6.1.12) (4.3.3)
Requirement already satisfied: pyzmq>=13 in ./.venv/lib/python3.6/site-packages (from jupyter-client==6.1.12) (22.0.3)
Requirement already satisfied: six>=1.5 in ./.venv/lib/python3.6/site-packages (from python-dateutil>=2.1->jupyter-client==6.1.12) (1.15.0)
Requirement already satisfied: ipython-genutils in ./.venv/lib/python3.6/site-packages (from traitlets->jupyter-client==6.1.12) (0.2.0)
Requirement already satisfied: decorator in ./.venv/lib/python3.6/site-packages (from traitlets->jupyter-client==6.1.12) (5.0.5)
Installing collected packages: jupyter-client
  Attempting uninstall: jupyter-client
    Found existing installation: jupyter-client 6.1.13
    Uninstalling jupyter-client-6.1.13:
      Successfully uninstalled jupyter-client-6.1.13
Successfully installed jupyter-client-6.1.12

$ pip list
Package          Version
---------------- -------
appnope          0.1.2
backcall         0.2.0
decorator        5.0.5
ipykernel        5.5.3
ipython          7.16.1
ipython-genutils 0.2.0
jedi             0.18.0
jupyter-client   6.1.12
jupyter-core     4.7.1
nest-asyncio     1.5.1
parso            0.8.2
pexpect          4.8.0
pickleshare      0.7.5
pip              21.0.1
prompt-toolkit   3.0.18
ptyprocess       0.7.0
Pygments         2.8.1
PyQt5            5.15.4
PyQt5-Qt5        5.15.2
PyQt5-sip        12.8.1
python-dateutil  2.8.1
pyzmq            22.0.3
qtconsole        5.0.3
QtPy             1.9.0
setuptools       54.2.0
six              1.15.0
tornado          6.1
traitlets        4.3.3
wcwidth          0.2.5
wheel            0.36.2

$ jupyter qtconsole
# At this point there is no output in the terminal, but the qtconsole window opens successfully

[ccordoba12]

Thanks a lot for reporting @carlosperate! I'll try to fix it as soon as possible.