First of all you should use AssertJ; FEST is outdated by this package. But since AssertJ shares a similar syntax, the transition will be easy.
Second, well, with AssertJ, this works out of the box... This compiles for me:
// irrelevant code, then
assertThat(findClass()).isEqualTo(Integer.class);
}
private Class<?> findClass()
{
return Integer.class;
}
So, maybe you have another problem?