def test_rank_negative():
"""A test to check that rank finds index of a key in sorted order."""
keys = list(range(-100, 100))
d = OrderedTreeDict((key, None) for key in keys)
assert all(list(keys[d.rank(k)] == k for k in keys))
def test_rank_simple():
d = OrderedTreeDict([(0, 0), (1, 1), (2, 2)])
assert len(d) == 3
assert (d.rank(0) == 0)
assert (d.rank(1) == 1)
assert (d.rank(2) == 2)