def test_reverse_cumulative_all_zero_warn(self):
histo = Histogram(bin_width=0.5, bin_range=(1.0, 3.5))
histo._histogram = collections.Counter({(0,): 0, (1,): 0})
with pytest.warns(UserWarning, match=r"No non-zero"):
rcumul = histo.reverse_cumulative()
assert rcumul(3.12) == 0
for val in rcumul.values():
assert val == 0
