Mockito matcher that compares items in Set, not the Set reference itself

Question

when(validator.isValid(Sets.newHashSet("valid"))).thenReturn(true);

When validator.isValid(set) is invoked it returns false. It is because the validator implementation creates a new set that is different that the passed one (reference is different) - the items in both sets are same.

I need to return true if sets contains same items regardless of sets instances.

Something similar to org.mockito.Matchers:

public static <T> Set<T> anySetOf(Class<T> clazz) {
        return (Set) reportMatcher(Any.ANY).returnSet();
}

except that I would pass instances not Class<T>.class.

And same for verify:

verify(validator, times(1)).isValid(Sets.newHashSet("valid"));

Is there such a matcher?

Answer 1

Apparently JB Nizet is right. There is no need for a specific matcher.

I have tried to use my own matcher and then after removal it worked also:

public static class SetItemMatcher extends ArgumentMatcher<Set<String>> {
    public static Set<String> setOf(Set<String> items) {
        return argThat(new SetItemMatcher(items));
    }

    private final Set<String> expected;

    public SetItemMatcher(Set<String> expected) {
        this.expected = expected;
    }

    @Override
    public boolean matches(Object argument) {
        Set<?> actual = (Set<?>) argument;
        return actual.size() == expected.size()  && containsAllItems(actual);
    }

    private boolean containsAllItems(Set<?> actual) {
        for (Object o : actual) {
            if (!expected.contains(o)) {
                return false;
            }
        }
        return true;
    }
}