pytester: Representation of the full collection tree, for testing collection hooks & plugins

[MusicalNinjaDad]

1. Am I reinventing the wheel here? and if not
2. is there an interest in a (more complete) version to be included in pytest?

I'm starting to put a plugin together which will include collection hooks. The How-To on Working with non-python tests suggests "While developing your custom test collection and execution it’s also interesting to just look at the collection tree:"

I'd rather have tests do this both during development and later for regression, along the lines of:

def test_collection(pytester):
    expected_tree = {...} # nested dict representation of collection tree
    # Some code to set up pytester
    assert CollectionTree.from_items(pytester.genitems([...]) == CollectionTree.from_dict(expected_tree)

[edit: removed conceptual example - it seems to detract from the questions asked, if the first reply is anything to go by...]

Any thoughts? Is this worth pursuing in a more generic context? or even personally within my own project (am I wasting time recreating something that already exists?)

[RonnyPfannschmidt]

Unfortunately its both incorrect and potential breaking on node tree changes

It removes the setup /teardown cost aware test reordering and it's fragile towards changes like the directory node introduction and the instance node removal

The eventually coming Definition node introduction would also break the expected trees there

[MusicalNinjaDad]

Yes, right now it is very much hacky-hack for my specific needs, and doesn't even fulfil those yet.

I just wanted to reach out early to see:

1. if something already existed in pytest which I'd not found and do I was watering my effort
2. If it was worth investing in covering cases I don't specifically need at the moment and upstreaming a correct and complete version