visual-studio-codevscode-debuggervscode-python

How can I get pytest to not catch exceptions


When I run pytest in the vscode debugger with "Uncaught Exceptions" checked, and there are test errors, no uncaught exceptions occur, because pytest catches them do its results reporting. How can I tell pytest to just let the exceptions happen? So that I can catch them in the vscode debugger?

Basically I want behavior like --pdb but I want it to launch the vscode debugger not pdb. The flag --pdbcls sounds promising but not sure what <module>:<class> to give it.

Note: Normally I would just have it break on Raised Exceptions. But our code has tons of raised-but-caught exceptions so this option is not useful.

Here's a video of vscode not breaking when an AssertionError fires while debugging a pytest test:

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@rioV8's suggestion below does break the on the exception, but for some reason there is no stack which means you can't debug from there:

enter image description here

I must be missing something because no one else seems to need this capability. But to me this seems like absolutely the most basic simplest thing one could do with a testing framework and a debugger: as a developer I want to debug from the point where the error is raised.

There must be some totally other way people are using a debugger with pytest, some obvious technique I'm overlooking.


Solution

  • I raised an issue with pytest and they made a suggestion that works. Add this to your conftest.py:

    import os
    import pytest
    
    if os.getenv('_PYTEST_RAISE', "0") != "0":
    
        @pytest.hookimpl(tryfirst=True)
        def pytest_exception_interact(call):
            raise call.excinfo.value
    
        @pytest.hookimpl(tryfirst=True)
        def pytest_internalerror(excinfo):
            raise excinfo.value
    

    Then in your "request": "test" launch.json you can toggle that env var:

        {
            "name": "Debug Tests",
            "type": "python",
            "request": "test",
            "console": "integratedTerminal",
            "justMyCode": true,
            "env": {
                "_PYTEST_RAISE": "1"
            },
        }
    

    If _PYTEST_RAISE is set and you check only the Uncaught Exceptions box you will break right where the uncaught exception was raised not before.

    I also opened an issue with debugpy and they had some ideas, but no solution today. The _PYTEST_RAISE trick works 100% solves this for me.