ArgumentMatcher for checking if two collection contains the same elements.

ContainsElements.java

    class ContainsElements<T> extends ArgumentMatcher<Collection> {
        private Collection<T> expected;
        public ContainsEqualElements(Collection<T> expected) {
            this.expected = expected;
        }
        public boolean matches(Object list) {
            if (list instanceof Collection) {
                Collection<T> actual = (Collection<T>) list;
                return actual.size() == expected.size() && actual.containsAll(expected) && expected.containsAll(actual);
            }
            return false;
        }
    }