public static IEnumerable<object[]> CompareTestData()
{
yield return new object[] { new Foo(5), new Bar(5), 0 };
yield return new object[] { new Bar(5), new Foo(5), 0 };
yield return new object[] { new Foo(1), new Bar(2), -1 };
yield return new object[] { new Bar(2), new Foo(1), 1 };
}