Modifying result of --collect-only

[Stefanhg]

Hello,
While testing https://github.com/scastlara/pytest-tagging
I came across something I expected work but didn't.
In an nutshell the plugin allows you to mark an testcase with a tag and then --tags (your_tag) will only run those tests with the tag.

The tests are then selected/deselected in the pytest_collection_modifyitems hook.
When using --tags (your_tag) --collect-only it will still display all available tests and not just those within the tagged item.

I looked though the code and it seems like the handling of --collect-only is not done after the collection. Is there another way allowing me to modify the collected result for --collect-only or will I have to add another custom argument to display the tagged items?

[bluetech]

When using --tags (your_tag) --collect-only it will still display all available tests and not just those within the tagged item.

Hmm, it should work. I just tested it with pytest's built-in -k and -m filters, which are both implemented with pytest_collection_modifyitems internally, and --collect-only only shows the filtered ones and the summary line reads 34/3551 tests collected (3517 deselected).

One thing that I'd try is change pytest-tagging pytest_collection_modifyitems implementation to not be a hookwrapper, I don't think there is any reason for it to be. I don't think it's related to what you're seeing but worth a try anyway.

[Stefanhg]

@bluetech Thanks for your reply.
I tried to remove the hookwrapper=True but this did not solve anything
If i add some debug info to pytest_collection_modifyitems it never enters the function when collecting. I also tried @pytest.mark.tryfirst

After some debugging it turns out for some reason this exact feature was actually bypassed! In pytest_configure it had a if not config.option.collectonly: in the register of the TaggerRunner class!