JUnit 4 compare Sets

Question

How would you succinctly assert the equality of Collection elements, specifically a Set in JUnit 4?

Answer 1

Using Hamcrest:

assertThat( set1, both(everyItem(isIn(set2))).and(containsInAnyOrder(set1)));

This works also when the sets have different datatypes, and reports on the difference instead of just failing.