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I'm unable to integrate my project's unit tests into VSCode. Test discovery fails because source files are not recognized by pytest.

(Just for clarification, this is a question about VSCode, not about pytest. I'm here because VSCode links its question section to SOF. Tests work fine if I run them manually.)

Tooling: pyenv, pipenv, pytest.

Project layout:

/src -> source code
/tests/unit -> test code

.vscode/settings.json:

{
    "python.envFile": "${workspaceFolder}/.env",
    "python.testing.pytestEnabled": true,
    "python.testing.pytestArgs": [
        "tests"
    ],
    "python.testing.unittestEnabled": false,
    "python.testing.nosetestsEnabled": false
    [...]
}

.env:

PYTHONPATH=./src

(Note: I don't think .env matters here, as per this comment, under Use of the PYTHONPATH variable)

Test discovery fails with:

tests/unit/test_revoke_default_sg.py:7: in <module>
    from revokedefaultsg.app import RevokeDefaultSg, UnknownEventException
E   ModuleNotFoundError: No module named 'revokedefaultsg'
=========================== short test summary info ============================
ERROR tests/unit/test_revoke_default_sg.py
!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
=============================== 1 error in 0.08s ===============================

This is caused by ./src not being part of the python path, so tests cannot import source code.

I can fix this on CLI/makefile level by adding to PYTHONPATH:

PYTHONPATH=./src pytest

This works as expected.

What's the correct setup for VSCode?

Am I supposed to create a launch configuration for testing? I've started to look into this, but couldn't get it to work nicely with pipenv.

Answers

(OP here)

I think the key to integrate into VSCode creating a specific launch configuration for pytest (before, I only had the default launch configuration that's been created with the Python extension).

I now have two configurations (.vscode/launch.json):

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Run Current File",
            "type": "python",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "env": {
                "PYTHONPATH": "./src"
            }
        },
        {
            "name": "Python: pytest",
            "type": "python",
            "request": "launch",
            "module": "pytest",
            "cwd": "${workspaceRoot}",
            "env": {
                "PYTHONPATH": "./src"
            },
            "envFile": "${workspaceRoot}/.env",
            "console": "integratedTerminal",
        }
    ]
}

(project on GitHub)

Running this configuration after launching VSCode discovers tests correctly, without raising errors. However, I have not tried it out in different projects yet.

Also, maybe I didn't find the right section of the VSCode documentation, but this feels heavily under-documented. I ended up searching GitHub for gists with launch configs and copied together whatever seemed vaguely helpful...