@Test
    void testEnablingOfCustomSessionValidationScheduler() {

        // using the default impl of sessionValidationScheduler, as the but effects any scheduler we set directly via
        // sessionManager.setSessionValidationScheduler(), commonly used in INI configuration.
        ExecutorServiceSessionValidationScheduler sessionValidationScheduler = new ExecutorServiceSessionValidationScheduler();
        DefaultSessionManager sessionManager = new DefaultSessionManager();
        sessionManager.setSessionValidationScheduler(sessionValidationScheduler);

        // starting a session will trigger the starting of the validator
        try {
            Session session = sessionManager.start(null);

            // now sessionValidationScheduler should be enabled
            assertTrue(sessionValidationScheduler.isEnabled(), "sessionValidationScheduler was not enabled");
        } finally {
            // cleanup after test
            sessionManager.destroy();
        }
    }
Tests a bug introduced by SHIRO-443, where a custom sessionValidationScheduler would not be started.
core/src/test/java/org/apache/shiro/session/mgt/DefaultSessionManagerTest.java