def test_subtraction_of_a_point_from_a_vector_raises_type_error(self):
v1 = Vector(3, 2, 1)
pt = Point(5, 6, 7)
with pytest.raises(TypeError):
# subtract a point from a vector makes no sense
v1.sub(pt)
def test_subtraction_of_two_vectors_results_in_a_vector(self):
v1 = Vector(3, 2, 1)
v2 = Vector(5, 6, 7)
rv = v1.sub(v2)
assert rv.to_tuple() == (-2, -4, -6, 0)
