pytest paramterized ids cannot be integers. They could in 2.9.2

test_ids.py

mport pytest


# -----------------------------------------
# To Demonstrate numerical ids not working
# -----------------------------------------


testdata = [( 1, 2), ( 2, 4)]

def times_2(x):
    return x * 2

@pytest.mark.parametrize("x,expected", testdata, ids=('a','b'))
def test_ids_strings(x,expected):
    '''works in both 3.0.0 and 2.9.2'''
    assert times_2(x) == expected


@pytest.mark.parametrize("x,expected", testdata, ids=(1,2))
def test_ids_numbers(x,expected):
    '''works in 2.9.2, crashes verbosely in 3.0.0'''
    assert times_2(x) == expected