def test_angle_to():
a = Quaternion()
b = Quaternion().set_from_euler(Euler(0, pi, 0))
c = Quaternion().set_from_euler(Euler(0, pi * 2, 0))
assert a.angle_to(a) == 0
assert a.angle_to(b) == pi
assert a.angle_to(c) == 0
def test_rotate_towards():
a = Quaternion()
b = Quaternion().set_from_euler(Euler(0, pi, 0))
c = Quaternion()
half_pi = pi * 0.5
a.rotate_towards(b, 0)
assert a.equals(a) is True
a.rotate_towards(b, pi * 2)
# test overshoot
assert a.equals(b) is True
a.set(0, 0, 0, 1)
a.rotate_towards(b, half_pi)
assert a.angle_to(c) - half_pi <= eps