def test_separate_by_order():
u, v = Variables('u v')
c, f = Constants('c f')
strong_form = StrongForm(c*grad(div(u)) + div(v) - f + dot(c, grad(u)))
order_dict = strong_form.separate_by_order()
assert(order_dict[0] == -f)
assert(order_dict[1] == div(v) + dot(c, grad(u)))
assert(order_dict[2] == c*grad(div(u)))
