def test_set_get_angle():
    "Test that set_angle() and get_angle() in Atoms are consistent"

    from ase import Atoms

    atoms = Atoms('HHCCHH', [[-1, 1, 0], [-1, -1, 0], [0, 0, 0],
                             [1, 0, 0], [2, 1, 0], [2, -1, 0]])

    list = [2, 3, 4]
    theta = 20
    old_angle = atoms.get_angle(*list)
    atoms.set_angle(*list, angle=old_angle + theta)
    new_angle = atoms.get_angle(*list)

    assert abs(new_angle - (old_angle + theta)) < 1.0e-9
