def test_opposite(self):
v = Vector([1, 0, 0])
u = Vector([-1, 0, 0])
assert pi == pytest.approx(v.angle(u))
assert 180 == pytest.approx(v.angle(u, unit="degrees"))
def test_perpendicular(self):
v = Vector([1, 0, 0])
u = Vector([0, 1, 0])
assert 1.570796326 == pytest.approx(v.angle(u))
assert 90 == pytest.approx(v.angle(u, unit="degrees"))
