Make test tags inherit from the class rather than be overridden by tags on the method

[William Ayd]

When subclassing test cases, decorated tags are inherited ONLY when the subclass does not provide its own tag decorator. If the subclass provides its own decorator(s) then the parent's tags are ignored.

If you use the attached file, running:

python manage.py test

yields two test cases as expected. However, running

python manage.py test --tag=foo-tests

OR

python manage.py test --tag=baz-tests

Will each only run one test a piece. I would expect that the former would run both test cases, given all of the test cases in the attached file are inherited from a class which is decorated with that tag.

[William Ayd]

test_foo.py

[Hrishikesh Barman]

Replying to William Ayd:

When subclassing test cases, decorated tags are inherited ONLY when the subclass does not provide its own tag decorator. If the subclass provides its own decorator(s) then the parent's tags are ignored.
Will each only run one test a piece. I would expect that the former would run both test cases, given all of the test cases in the attached file are inherited from a class which is decorated with that tag.

I am a new contributor, I might be completely wrong but I think this is how the tag decorator is supposed to work. When a parameter is explitcitly passed into the tag decorator, the function should use that tag and if the need is to specify another tag it should be done by separating by commas.

 @tag('slow', 'core')
 def test_slow_but_core(self):
   pass

docs: ​https://docs.djangoproject.com/en/1.11/topics/testing/tools/#tagging-tests

If this is a confirmed bug, I'd like to work on it if you let me. :)

[William Ayd]

Hi Hrishikesh,

My point was that it's strange that FooBar inherits the tag from it's parent while FooBaz does not, simply because the latter adds another tag of its own. Either neither class should inherit the tag from its parent, or both of them should (I think both inheriting would be preferred).

From what I see this can be easily fixed changing the tag function in Django.tests.util from:

def tag(*tags):
    """
    Decorator to add tags to a test class or method.
    """
    def decorator(obj):
        setattr(obj, 'tags', set(tags))
        return obj
    return decorator

To

def tag(*tags):
    """
    Decorator to add tags to a test class or method.
    """
    def decorator(obj):
        if hasattr(obj, 'tags'):
            obj.tags = obj.tags | set(tags)
        else:
            setattr(obj, 'tags', set(tags))
        return obj
    return decorator

So that subclasses can inherit any existing tags from their parents

[Simon Charette]

The proposed fix looks appropriate.

Please submit a PR with your proposed patch and a regression test in ​tests/test_runner/test_discover_runner.py based on the structure introduced by d4dc775620fc57e962165eab98a77264e3dd16b2.

[Hrishikesh Barman]

Hello William,

I understand it now. thanks. :)

[William Ayd]

Please note that I have fixed this and included regression tests in branch ticket_28869 available in my GitHub repo

​https://github.com/WillAyd/django/tree/ticket_28869

[Tim Graham]

I left comments for improvement on the PR.

[Tim Graham <timograham@…>]

In 09530e61:

Fixed #28869 -- Made tagged test classes and methods inherit tags from parents.