Tox Plugin: Add additional dependencies to environment?

[hansingt]

Hi!

I'm currently developing a tox plugin, to allow automatic provisioning of NodeJS using the nodeenv package.

What I'm not sure about now is, whether it's possible to programatically declare additional environment deps from within the plugin.

My Idea was, that the user simply defines a nodejs=<version> option in the tox env and this results in automatic provisioning of the corresponding NodeJS version. E.g.:

[tox]
requires = tox-nodeenv

[testenv]
nodejs=lts

So, my question would be: Is is possible to somehow declare, an additional environment dependency in a tox plugin?
Simply using tox_env.conf["deps"].append() does not work, because tox_env.conf["deps"] returns a PythonDeps object, which does not define a append() method.

[gaborbernat]

You should not combine the tox and node environments. They should be separate. Within tox 4 you are supposed to implement https://github.com/tox-dev/tox/blob/main/src/tox/tox_env/runner.py#L1 and also implement a node packaging/installer there.

[hansingt]

Thanks for the reply.

You should not combine the tox and node environments. They should be separate.

Can you explain why this should not be done?

Within tox 4 you are supposed to implement https://github.com/tox-dev/tox/blob/main/src/tox/tox_env/runner.py#L1 and also implement a node packaging/installer there.

So, if I get you right, I should implement a custom RunToxEnv and then implement the provisioning within the setup() Method, right?
How does this behave if I have multiple plugins defining custom RunToxEnvs? Will this be possible?

Sorry for the stupid questions, I'm new to tox development.

[gaborbernat]

The PythonToxEnv as it's naming implies is only valid/defined for handling python environment and code. You need to implement a node one to handle that case. You will end up having a separate environment for your node code, and the separate for your python. You could also combine them by creating a plug-in that merges two environment. However, that can get tricky.