[pytest-dev] mark fix-up major milestone, please review

[Floris Bruynooghe]

On Tue, Mar 20 2018, Ronny Pfannschmidt wrote:

> 2018-03-20 9:18 GMT+01:00 Floris Bruynooghe <flub at devork.be>:
>> On Mon, Mar 19 2018, Ronny Pfannschmidt wrote:
>> > I also did deprecate markinfo attributes,
>> > so everyone using them will get deprecation warnings.
>>
>> That's a lot of people probably.  How long are we giving users for this?
>> ​
>>
>
> ​the support for accessing them can be kept for quite a while,
> everyone using them will be told to use the new api
> i would like to remove it at the beginning of 2019

Ok, they're currently marked as "deprecated in 4.0".  So we're not
releasing 4.0 until then?  Or are we just keeping our options open here
and extending a deprecation is easier then reducing it?

>> > as far as i'm concerned, markinfo attributes where never ever a correct
>> way
>> > to handle distinct marks and quite a few bugs in pytest came from using
>> > combined marks in markinfo instead of distinct marks.
>>
>> A short summary of these issues would help loads :)
>>
> ​basically MarkInfo objects are subject to marker transfer bugs, marker
> smearing and everything wrong with marks these days
> they are one of holgers infamous minimal changes that basically ensured we
> never ever had correctly working marks
> from the time we had support for more than one marker of the same name, and
> it got worse by the addition of marker transfers
> (for context - pytest marks started as thing to update test function
> __dict__ with its keyword arguments,
> they never got de-tangled from that messy legacy, and that was a major
> source of really bad bugs)

Thanks!  Could you give an example of a marker transfer bug?  I've never
run into those myself so I'm not sure I understand what this is.  I
assume something like this will trigger weird cases:

@pytest.mark.mark0
class Foo:

    @pytest.mark.mark1
    def test_foo(self):
        pass

    @pytest.mark.mark0('foo', a='a')
    def test_bar(self):
        pass

So the new API to inspect this is (in some pseudo-code like fashion):

<Item name=test_foo>.get_marker('mark0') -> Mark(name='mark0')
<Item name=test_foo>.get_marker('mark1') -> Mark(name='mark1')
<Item name=test_bar>.get_marker('mark0') -> ??
list(<Item name=test_foo.find_markers('mark0')) -> [Mark(name='mark0')]
list(<Item name=test_bar.find_markers('mark0')) -> ??

Also, can I iterate over all the markers on a node?


Thanks for educating me!
Floris