def test_statistic_can_be_created_from_list():
data = [1, 2, 3]
st = Statistic(data)
assert len(st) == 3
assert not st.empty
assert st.as_list() == [1, 2, 3]
assert st.as_tuple() == tuple(data)
assert st.as_list() is not data # check that data was copied
def test_statistic_is_initially_empty():
st = Statistic()
assert len(st) == 0
assert st.empty
assert st.as_list() == []
assert st.as_tuple() == ()