Fix GitHub Action CI workflow tests with Python 3.8 and 2.7

[kimadeline]

The CI workflow runs the test suites against Python 2.7 and 3.8, which are not the versions used in the CI pipeline in Azure Pipelines (3.6 and 3.7).

Python tests are failing when run on 3.8, but passing on 3.7, with failures seemingly related to pytest.

Todo:

• Use pytest 4.6.9 for our Python tests (Run Python and IPython unit tests step)
• Fix other Python 3.8 test failures that may arise
• Double-check that we didn't break tests, fix them otherwise

Note: Since the changes needed are pipeline-independent we might be able to close #8298 after this.

[kimadeline]

#10276 fixed #8298, now see if we need to make additional changes for this issue (we shouldn't need to).

[kimadeline]

Seems like there's an issue when running the debugger tests on Python 2.7 (something we don't do on AzDO): https://github.com/microsoft/vscode-python/runs/472170446?check_suite_focus=true

Unhandled error. ({
  seq: 0,
  type: 'event',
  event: 'error',
  body: 'Debugger Error: The number of constructor arguments ' +
    'in the derived class ProtocolParser must be >= than ' +
    'the number of constructor arguments of its base ' +
    'class.'
}): Error [ERR_UNHANDLED_ERROR]: Unhandled error. ({
  seq: 0,
  type: 'event',
  event: 'error',
  body: 'Debugger Error: The number of constructor arguments ' +
    'in the derived class ProtocolParser must be >= than ' +
    'the number of constructor arguments of its base ' +
    'class.'
})

  at DebugClient.emit (events.js:189:17)
    at DebugClient.dispatch (/home/runner/work/vscode-python/vscode-python/node_modules/vscode-debugadapter-testsupport/src/protocolClient.ts:138:9)
    at DebugClient.handleData (/home/runner/work/vscode-python/vscode-python/node_modules/vscode-debugadapter-testsupport/src/protocolClient.ts:109:12)
    at Socket.<anonymous> (/home/runner/work/vscode-python/vscode-python/node_modules/vscode-debugadapter-testsupport/src/protocolClient.ts:31:9)
    at Socket.emit (events.js:200:13)
    at addChunk (_stream_readable.js:294:12)
    at readableAddChunk (_stream_readable.js:275:11)
    at Socket.Readable.push (_stream_readable.js:210:10)
    at Pipe.onStreamRead (internal/stream_base_commons.js:166:17)

    1) Ensure messages are not received after disposing the parser

Edit: Fixed with PR #10410

[kimadeline]

All failures:

• ubuntu, py27, venv: https://github.com/microsoft/vscode-python/runs/484534820?check_suite_focus=true
• ubuntu, py38, smoke tests (timeouts): https://github.com/microsoft/vscode-python/runs/484534820?check_suite_focus=true
• ubuntu, py27, single-workspace https://github.com/kimadeline/vscode-python/actions/runs/61591660
• ubuntu, py27, multi-workspace https://github.com/kimadeline/vscode-python/actions/runs/61614453
• windows, py38, venv https://github.com/kimadeline/vscode-python/actions/runs/61609933
• windows, py38, multi-workspace https://github.com/kimadeline/vscode-python/actions/runs/61606594
• windows, py38, smoke https://github.com/kimadeline/vscode-python/actions/runs/61611930
• windows, py27, venv https://github.com/kimadeline/vscode-python/actions/runs/61755168

[rchiodo]

@kimadeline will this bug fix the 3.8 failures on the CI system?
https://dev.azure.com/ms/vscode-python/_build/results?buildId=73356&view=ms.vss-test-web.build-test-results-tab
Doesn't seem like it but I wasn't sure. The failures I'm seeing are in unit tests for windows 3.8. I believe Don just added the ipywidget failures, but I've been seeing the terminal and interpreter failures before that.

[kimadeline]

The 3.8 unit tests (Ubuntu and Windows) were passing in GitHub Actions when this issue was created, so this is new. We should probably verify these test suites again though.

[kimadeline]

Stale issue, closing 🥖