}
@Test
public void commandHandlerRegistration() throws Exception {
LayerCommandFixture command = new LayerCommandFixture();
CommandHandlerFixture commandHandler = new CommandHandlerFixture();
dataLayer.registerCommandHandler(commandHandler);
dataLayer.doCommand(command);
assertNotNull(commandHandler.getLastCommandHandled());
commandHandler.clearLastCommandHandled();
dataLayer.unregisterCommandHandler(command.getClass());
dataLayer.doCommand(command);
assertNull(commandHandler.getLastCommandHandled());
}