Parallelism doesn't work when pytest is run through tox

[LKay]

My tests are orchestrated by tox and part of my tox.ini config looks like this:

[testenv]
deps = pipenv
setenv =
    PYTHONPATH = {toxinidir}
whitelist_externals = {homedir}/.local/share/virtualenvs/*
commands =
    pipenv sync --dev
    pipenv run pytest --circleci-parallelize --junitxml=test-results/{envname}/results.xml tests/ {posargs}

I am trying to execute tests in parallel on CircleCI and parameter from the plugin is recognized correctly and outputs message:

collected 5 items                                                              
running 5 items due to CircleCI parallelism

However all test cases are run in full on every instance and are not redistributed between nodes.

[ryanwilsonperkin]

Is tox correctly copying the environment variables into the subcommands that it creates to run your pipenv steps?

[ryanwilsonperkin]

You may need to specify passenv in your tox.ini