BOOST_AUTO_TEST_CASE(must_have_a_valid_addition_assignment)
	{
		int x = 3, y = 5, z = 6;
		(x += y) += z;

		CRational rx(3);
		CRational ry(5);
		CRational rz(6);
		(rx += ry) += rz;
		BOOST_CHECK(rx == x);
	}