@Test public void testIsEmpty() { SideInputHandler sideInputHandler = new SideInputHandler(ImmutableList.of(view1), InMemoryStateInternals.<Void>forKey(null)); assertFalse(sideInputHandler.isEmpty()); // create an empty handler SideInputHandler emptySideInputHandler = new SideInputHandler(ImmutableList.of(), InMemoryStateInternals.<Void>forKey(null)); assertTrue(emptySideInputHandler.isEmpty()); }