Add config_settings support for build backend calls

[nschloe]

This is a first (non-working) stab at #3080. I tried to add a config setting just like #1891, but it doesn't seem to get passed on to self.core. It's supposed to be used like

[testenv]
config_settings = 
  abc = xyz

Any hints on what's missing?

[nschloe]

The current implementation allows

[testenv:.pkg]
pep517_config_settings = 
  a = b
  x = yz

[gaborbernat]

You likely want to have a base settings and then allow overriding for wheel/sdist/editable.

[nschloe]

Do you mean something like

[testenv:.pkg]
pep517_config_settings_base = 
  a = b
  x = yz
pep517_config_settings_sdist = 
  a = c
  x = z
pep517_config_settings_wheel = 
  a = W
  x = W

? In the interest of keeping things simple, I'm not convinced that's necessary. After all, there's a separate setting for sdist/wheel/editable builds, and when the user wants to change that, she has to touch the config anyway. E.g., from

[testenv:.pkg]
package = editable
pep517_config_settings = 
  a = b
  x = yz

to

[testenv:.pkg]
;package = editable
;pep517_config_settings = 
;  a = b
;  x = yz
package = sdist
pep517_config_settings = 
  a = S
  x = S

What do you think?

[gaborbernat]

Multiple different tox environments can reuse the same packaging environment, so it's important they are configurred differently:

[testenv]
wheel_build_env = .pkg

[testenv:wheel]
package = wheel


[testenv:sdist]
package = sdist

[testenv:editable]
package = editable

All these 3 envs will use the same .pkg and its settings even though they build differently.

[nschloe]

Ah, so what should the config look like exactly?

[gaborbernat]

[testenv]
wheel_build_env = .pkg

[testenv:wheel]
package = wheel


[testenv:sdist]
package = sdist

[testenv:editable]
package = editable

[testenv:.pkg]
config_settings = 
  a = S
config_settings_wheel = 
  a = S
config_settings_sdist = 
  a = S
config_settings_editable = 
  a = S

If config_settings_wheel is not set defaults to config_settings and so on.

[nschloe]

If

config_settings = 
  a = S
  b = T
config_settings_wheel = 
  a = U

should the complete list of config settings by

  a = U
  b = T

or

  a = U

?

[gaborbernat]

Don't merge. Instead override.

[nschloe]

What about the self._wheel_config_settings?

[gaborbernat]

Add tests too please.

[nschloe]

What about the self._wheel_config_settings?

self._wheel_config_settings is now overridden my either of the other config_settings (if present).

[nschloe]

Add tests too please.

Where would they go? tests/conftest.py?

[nschloe]

I'm having substantial problems setting up a test. There seems to be no similar test prototype I could take inspiration from. For example meta_dir and pkg_dir don't appear in the tests at all. That's not mentioning that I have no idea how to test if the arguments are actually passed through.

[nschloe]

@gaborbernat I'm gonna need some guidance here.

[gaborbernat]

Will need tox-dev/pyproject-api#99 first released.

[gaborbernat]

[webknjaz]

@nschloe did you forget to use your own username here?

[nschloe]

Not really. I made some contributions here, but Gabor finished it all up.

[webknjaz]

Ah, I see. Well, you can always enumerate several people..
Thanks for the contrib, by the way! I was just checking if tox already handles the config settings and found this :)

[webknjaz]

@nschloe I don't see any mentions of just config_settings that is not hook-specific but shared. Did that end up not being implemented?

[nschloe]

Don't remember. Maybe @gaborbernat knows something here.

[gaborbernat]

We did not add that, but you can do that with config reference in your tox file.

[webknjaz]

@gaborbernat do you mean compute dynamically in a toxfile.py?

[gaborbernat]

No, I meant just set it once in tox.ini and use config reference to set it for every hook you care about.

[webknjaz]

@gaborbernat when you say “config reference”, what exactly do you mean? I'm guessing that's what I don't understand. Could you help me bridge the gap in understanding?

[gaborbernat]

https://tox.wiki/en/4.21.2/config.html#configuration-reference

[gaborbernat]

refering to another config in the config file

[webknjaz]

Ah, I didn't know about that new syntax. The old one was substitutions. Thanks!

[gaborbernat]

Technically, the old one was reference with substitution (because in INI text is text, so what's the difference). The new one is separated because TOML has types, and text != array.