def test_segment_normal_3d():
a = np.array([1, 1, 0])
b = np.array([1, 10, 0])
p = np.array([1, 0, 0])
unit_norm = segment_normal(a, b, p)
assert np.all(unit_norm == np.array([0, 0, -1]))
def test_segment_normal_2d():
a = np.array([1, 1])
b = np.array([1, 10])
unit_norm = segment_normal(a, b)
assert np.all(unit_norm == np.array([1, 0]))
