def test_twolens_bfl_matches_efl_in_contact():
efl1, efl2 = 2.0, 2.0
assert thinlens.twolens_bfl(efl1, efl2, 0) == efl1 / 2
def test_twolens_bfl_general(twolens_params):
efl1, efl2, t = twolens_params
assert thinlens.twolens_bfl(efl1, efl2, t)