Question about --skip-env-install

[thomas-saigre]

Hi !

I'm trying to set up tox so that I can run the tests when I'm offline (and also avoid re-downloading all dependencies each time I run the command).
If I have understood correctly, by default each time I run tox -- --cov tikzplotly --cov-report html --cov-report term, it recreates the environment, downloads all dependencies, and runs tests and collects coverage.

I discovered the option --skip-env-install that skips the construction of the environment.
But it seems that it also skips the update of the package I'm developing.

For testing, I added assert False at the very beginning of the main function of my library (which is called in almost all tests), but even with this, all tests passes :

===================================================================== 76 passed in 12.86s ======================================================================
  py3: OK (14.08=setup[0.04]+cmd[0.20,13.83] seconds)
  congratulations :) (14.10 seconds)

Just to be sure, when I remove the option, the tests are indeed failling :

================================================================= 74 failed, 2 passed in 7.74s =================================================================
py3: exit 1 (8.61 seconds) ~/Documents/code/tikzplotly> pytest --cov tikzplotly --cov-report html --cov-report term pid=211619
  py3: FAIL code 1 (11.82=setup[3.01]+cmd[0.20,8.61] seconds)
  evaluation failed :( (11.85 seconds)

Is there something I got wrong ?

Thanks !!

[gaborbernat]

Hi! This is working as documented — --skip-env-install skips both dependency installation and building/installing your package (it is a superset of --skip-pkg-install), so your tests ran against the previously installed wheel, which is why the assert False was not seen.

Note that by default tox 4 does not recreate the environment or re-download dependencies on every run — environments are reused and deps are only reinstalled when their configuration changes. The only per-run cost is rebuilding and reinstalling your package, which is what makes your code changes visible.

If you want to skip even that, use an editable install so the environment points directly at your source tree:

[testenv]
package = editable

With that, source changes are picked up without any reinstall, and you can combine it with --skip-env-install for fully offline runs (just remember dependency/metadata changes still need a normal run to be applied).