How to add marks to tests added using metafunc?

I have some code that generates one test for each .yaml file in a folder.

def pytest_generate_tests(metafunc):
    if "yamlpath" in metafunc.fixturenames:
        files = []
        names = []
        for filename in os.listdir(YAML_FILES_FOLDER):
            if filename.endswith('.yaml') or filename.endswith('.yml'):
                testname = filename.split('.')[0]
                files.append(YAML_FILES_FOLDER / filename)
                names.append(testname)

        metafunc.parametrize("yamlpath", files, ids=names)

However, a few of my tests are failing. Therefore, I would like to mark some of them as xfail. How can I do this?

One way could do it is add one more parameter to your test function that indicates that the test is expected to fail and then you add a

if fails:
    pytest.xfail()

branch to the start of the test to mark the test using code. You then pass the fails argument when generating tests.

I made a simpler example with where I just check if a number is even

# conftest.py

def pytest_generate_tests(metafunc):
    if "number" in metafunc.fixturenames:
        names = ["number", "fails"]
        values = []
        for i in range(1, 3):
            values.append([i, not (i % 2 == 0)])
        metafunc.parametrize(names, values)


# test_1.py

import pytest

@pytest.fixture
def number():
    pass

def test_1(number, fails):
    if fails:
        pytest.xfail(reason="Should fail")
    assert number % 2 == 0

def test_2():
    assert True

def test_3():
    assert False

This should work for most other marks as well, since most of them seem to have an equivalent function.