Open
Description
Issue
In userver, we add indirect params to all tests based on marks using pytest_generate_tests.
(See the full story in #13217.)
The issue arises when we want to apply our implicit param only to some of the test items spawned from an already parametrized test:
@pytest.mark.parametrize(
"foo, bar",
[
("a", "x"),
pytest.param("b", "y", marks=pytest.mark.my_mark("hmm")),
pytest.param("c", "z", marks=pytest.mark.my_mark("what")),
])
def my_test(foo, bar, my_fixture, ...):
# ...
def pytest_parametrize_tests(metafunc):
# metafunc represents a test function before the split into items.
# How do we set indirect param "my_fixture" based on marks
# from one of the cases?The issue has been previously explored: #4050
Proposed syntax
What I want to discuss here is an implementation of that idea, starting with a possible syntax.
# pytest
@dataclasses.dataclass(frozen=True)
class ProtoItem(pytest.Node):
# essentially CallSpec2 with a rich API from Node
params: dict[str, object]
own_markers: list[Mark]
# usage
def pytest_parametrize_tests(metafunc):
def param_generator(proto_item: pytest.ProtoItem) -> ParameterSet | Sequence[object] | object:
if (mark := proto_item.get_closest_marker("my_mark")) is not None:
return (compute_param_value_from_mark(mark),)
else:
return (get_some_fallback_value(),)
metafunc.parametrize(("my_fixture",), param_generator)