I wrote a post about how to Unit testing your UIViewController been pushed properly

Usage

#import "UIViewController+MockUINavigationController.h"

- (void)testViewControllerBeenPushedProperly
{
  CustomViewController *viewController = [[CustomViewController alloc] init];
  [viewController pushIt];
  [MKTVerify(viewController.navigationController) pushViewController:anything() animated:YES];
}

My matcher is OCHamcrest, mocking library is OCMockito.