@Test
    void testAttributeNames() {
        val attributeSources = new ArrayList<PersonAttributeDao>();
        attributeSources.add(sourceOne);
        attributeSources.add(sourceTwo);

        var impl = new MergingPersonAttributeDaoImpl();
        impl.setPersonAttributeDaos(attributeSources);

        var attributeNames = impl.getPossibleUserAttributeNames(PersonAttributeDaoFilter.alwaysChoose());
        assertEquals(oneAndTwo.keySet(), attributeNames);
    }
Testcase for {@link StubPersonAttributeDao}.

@author Misagh Moayyed
@since 7.1.0
core/cas-server-core-authentication-api/src/test/java/org/apereo/cas/authentication/attribute/MergingPersonAttributeDaoImplTests.java