parameterize argvalues with a mapping

[ikonst]

The current syntax for providing an id along with a parameter set is:

@pytest.mark.parameterize('a,b', [
    pytest.param(1, 3, id='odds'),
    pytest.param(2, 4, id='evens'),
])
def test_something(a, b):
    ...

I'd like to get peoples' opinions about an alternative syntax:

@pytest.mark.parameterize('a,b', {
    'odds': (1, 3),
    'evens': (2, 4),
})
def test_something(a, b):
    ...

The rationale, other than the alternative being shorter, is that (it seems to me) that mappings are natural for pairing identifiers and data. If we have to decide on a way to interpret someone passing a mapping into argvalues, I think that'll be a natural one.

P.S. currently, if you pass a dictionary as argvalues, its keys are iterated and the values are discarded

[pytestbot]

GitMate.io thinks possibly related issues are #3196 (How to parameterize the entire test suite?), #1263 (mapping the fixture parameter with the test method parameter), #120 (py.test.mark.parameterize works with test functions, but not classes), and #423 (Consecutive pytest.mark.skipif inside pytest.mark.parameterize).

[nicoddemus]

Hi @ikonst,

Thanks for writing!

I like the idea, but I'm -1 on adding yet another way to parametrize values, as we would still need to keep the old ways working.

[RonnyPfannschmidt]

this was proposed before and rejected

[nicoddemus]

I see, let's close this then. Once again thanks @ikonst for the suggestion!

[ikonst]

Do you remember what was the rationale for rejection before? “yet another”?

[RonnyPfannschmidt]

@ikonst it couldn't sanely support features like adding markers to certain calls