如何对didFinishLaunchingWithOptions进行单元测试？

Question

I am following the book "Test-Driven iOS Development" by Graham Lee and came across this section that isn't well explained at all. The idea is not to instantiate UIWindow in the didFinishLaunchingWithOptions but rather using an IBOutlet and hook it to an UIWindow xib file. I can't get that working and can't find any example on the internet.

-(void)testWindowHasRootNavigationControllerAfterApplicationLaunch
{
    XCTAssertEqualObjects(window.rootViewController, navigationController, @"App delegate's navigation controller should be the root VC");
}

@implementation iTagNewsAppDelegateTests
{
    UIWindow *window;
    UINavigationController *navigationController;
    AppDelegate *appDelegate;
}

- (void)setUp {
    window = [UIWindow new];
    navigationController = [UINavigationController new];
    appDelegate = [AppDelegate new];
    appDelegate.window = window;
    appDelegate.navigationController = navigationController;
}

Code:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
BrowseOverflowViewController *firstViewController =
[[BrowseOverflowViewController alloc] initWithNibName: nil bundle: nil];
    TopicTableDataSource *dataSource = [[TopicTableDataSource alloc]
        init];
    [dataSource setTopics: [self topics]];
    firstViewController.dataSource = dataSource;
    self.navigationController.viewControllers =
        [NSArray arrayWithObject: firstViewController];
    self.window.rootViewController = self.navigationController;
    [self.window makeKeyAndVisible];
    return YES;
}

@interface BrowseOverflowAppDelegate : NSObject <UIApplicationDelegate> 
@property (nonatomic, retain) IBOutlet UIWindow *window;  
@property (nonatomic, retain) IBOutlet UINavigationController *navigationController;
@end

His full project is on GitHub. Is there any tutorial how to define a custom UIWindow ? many thanks

Answer 1

I haven't read that book but found that I was able to test a full instance of my AppDelegate. Adapting it to your code:

- (void) setUp {
    //Could also use [[UIApplication sharedApplication] delegate] but I'm worried state may persist
    iTagNewsAppDelegate* appDelegate = [[iTagNewsAppDelegate alloc] init]
    [appDelegate application:[UIApplication sharedApplication] didFinishLaunchingWithOptions:nil]; //Couldn't find a better option than sharedApplication here, fine if application param isn't used?
    //the rest of your setup here
}

This works in my project but I'm not sure about the side effects of using sharedApplication. You want a unit test to have a known beginning state and reusing the running app throughout your tests is usually a bad thing.