### Question:
RedoSessionCommand extends AbstractClientSessionCommand<EditorSession> { void onCurrentRegistryChanged(final @Observes CurrentRegistryChangedEvent currentRegistryChangedEvent) { checkState(); } protected  RedoSessionCommand(); @Inject  RedoSessionCommand(final SessionCommandManager<AbstractCanvasHandler> sessionCommandManager,
                              final RedoCommandHandler<Command<AbstractCanvasHandler, CanvasViolation>> redoCommandHandler); @Override void bind(final EditorSession session); @Override boolean accepts(final ClientSession session); @Override @SuppressWarnings("unchecked") void execute(final Callback<V> callback);  }### Answer:
@Test public void testOnCurrentRegistryChanged() { final CurrentRegistryChangedEvent event = mock(CurrentRegistryChangedEvent.class); ((RedoSessionCommand)command).onCurrentRegistryChanged(event); verify((RedoSessionCommand)command).checkState(); }