@Test
public void testGetApplicationSecret() {

    assertEquals(ZTSUtils.getApplicationSecret(null, "appname", "pass"), "pass");
    
    PrivateKeyStore keyStore = Mockito.mock(PrivateKeyStore.class);
    Mockito.when(keyStore.getApplicationSecret(null, "pass")).thenReturn("app234");
    assertEquals(ZTSUtils.getApplicationSecret(keyStore, null, "pass"), "app234");
    
    Mockito.when(keyStore.getApplicationSecret("appname", "passname")).thenReturn("app123");
    assertEquals(ZTSUtils.getApplicationSecret(keyStore, "appname", "passname"), "app123");
}