@Test
    void testGetRememberedPrincipalsWithEmptySerializedBytes() {
        AbstractRememberMeManager rmm = new DummyRememberMeManager();
        //Since the dummy's getRememberedSerializedIdentity implementation returns an empty byte
        //array, we should be ok:
        PrincipalCollection principals = rmm.getRememberedPrincipals(new DefaultSubjectContext());
        assertNull(principals);

        //try with a null return value too:
        rmm = new DummyRememberMeManager() {
            @Override
            protected byte[] getRememberedSerializedIdentity(SubjectContext subjectContext) {
                return null;
            }
        };
        principals = rmm.getRememberedPrincipals(new DefaultSubjectContext());
        assertNull(principals);
    }
Tests the {@link AbstractRememberMeManager#getRememberedPrincipals(SubjectContext)} method
implementation when the internal
{@link AbstractRememberMeManager#getRememberedSerializedIdentity(SubjectContext)} method
returns null or empty bytes.
core/src/test/java/org/apache/shiro/mgt/AbstractRememberMeManagerTest.java