[pytest-dev] Proposal: python namespacign for markings/marker objects

[Floris Bruynooghe]

On 7 September 2016 at 10:38, Ronny Pfannschmidt <rpfannsc at redhat.com> wrote:
> Hi all,
>
> while trying to turn various internal markers of a work project
> into public plugins, i noticed a very plain problems - different other
> plugins used the same generic marker name for different purposes/intents
>
> such a flat namespace really doesn't scale
>
> as such i would like to propose having marker types and objects as
> importable objects
>
> for example
>
> import pytest
> from pytest_bugzilla import Blocker
>
> @pytest.mark(Blocker(123))
> def test_fun():
>   pass
>
> that way we can do both, reuse python name-spacing *and* use more meaningful
> objects for markings

I'm rather lukewarm for this proposal to be honest.  We already have
an API which allows creating of mark objects for later re-use:

blocker = pytest.mark.bugzilla_blocker

@blocker
def test_fun():
    pass

So instead of changing the way way pytest.mark behaves I think it
might be more interesting to look at alternative ways of creating
marker objects.  E.g. if you could do:

# pytest_bugzilla.py
class Blocker(pytest.MarkerObject):
    def __init__(self, n):
        pass

# test_fun.py
from pytest_bugzilla import Blocker

@Blocker(123)
def test_fun():
    pass

Then you can still import your marker and you also get more strict
namespacing since you created a unique object in your module.  But the
benefit is that from the point of view of using markers not much has
changed.  There's just a new way of creating markers.

What do you reckon about such an approach?


Finally, and I only just remembered, Holger has some lingering code
somewhere which does something like:

@pytest.marker
def blocker(n):
    return {'issue no': int(n)}  # or whatever object you want your marker to be

@pytest.mark.blocker(123)
def test_fun():
    pass

This uses symmetry with how we create fixtures, which is nice.  But it
does not solve the namespacing issue, which to some extend also exists
in fixtures.  Just brainstorming to add something namespace like to
that would be:

@pytest.marker(ns='bugzilla')
def blocker(n):
    return int(n)

@pytest.mark.bugzilla.blocker(123)
def test_fun():
    pass

I admit this does not re-use the python module namespaces, which is
probably a downside.


Floris