returning error messages about custom options?

[rvandegrift]

Hello,

My conftest.py defines some extra options. I'd like to validate the input and return detailed error messages if it's wrong, but I can't figure out how to do that. Here's a silly example:

def wooo(value):
    if value != 'wooo':
        raise ValueError(f'{value} is not equal to wooo')


def pytest_addoption(parser):
    parser.addoption('--wooo', action='store', required=True, type=wooo)

When I provide bad input, pytest swallows my error message and replaces it with a generic one:

$ python3 -m pytest --wooo=asdf
ERROR: usage: __main__.py [options] [file_or_dir] [file_or_dir] [...]
__main__.py: error: argument --wooo: invalid wooo value: 'asdf'

Is there any way to get my validation's error returned to the user?

[The-Compiler]

That's a feature of the underlying argparse module.

You could raise a pytest.UsageError instead, which will instead display:

$ pytest  --wooo=asdf
ERROR: asdf is not equal to wooo

[rvandegrift]

awesome, that works - I've opened #8610 to add some details on this to the docs.