Automated testing of segues

Question

I want to create an integration test which shows that a certain action results in the display of a modal view controller. The storyboard is setup with 2 viewcontrollers, one with a custom ViewController class the second with a default UIViewController class and title "second". The segue is set-up to be modal with identifier "modalsegue". Running the app in the simulator works brilliantly, but I am having a lot of trouble defining a correct test.

ViewController.m:

@implementation ViewController

- (IBAction)handleActionByPerformingModalSegue {
    [self performSegueWithIdentifier:@"modalsegue" sender:self];
}
@end

Test:

- (void)testActionCausesDisplayOfSecondViewController {
    ViewController * vc =
      [[UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil]   
          instantiateViewControllerWithIdentifier:@"ViewController"];

    [vc handleActionByPerformingModalSegue];
    STAssertEquals(vc.presentedViewController.title, @"second",
        @"Title of presented view controller should be second but is %@",   
        vc.presentedViewController.title, nil);
}

Running the test results in the following output:

2013-06-23 17:38:44.164 SeguesRUs[15291:c07] Warning: Attempt to present <UIViewController: 0x7561370> on <ViewController: 0x7566590> whose view is not in the window hierarchy!
SeguesRUsTests.m:33: error: -[SeguesRUsTests testActionCausesDisplayOfSecondViewController] : '<00000000>' should be equal to '<9c210d07>': Title of presented view controller should be second but is (null)

What am I doing wrong? Is there an easy way to avoid the first message?

Answer 1

As the error message points out, the problem is that you're trying to present on a UIViewController whose view is not in the UIWindow hierarchy.

The easiest way to fix it:

- (void)testExample {

    //
    // Arrange
    // Storyboard
    //
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];

    //
    // Arrange
    // View Controller
    //
    UIViewController *viewController = [storyboard instantiateViewControllerWithIdentifier:@"ViewController"];
    [UIApplication sharedApplication].keyWindow.rootViewController = viewController;

    //
    // Act
    //
    [viewController performSegueWithIdentifier:@"ModalSegue" sender:nil];

    //
    // Assert
    //
    XCTAssertEqualObjects(viewController.presentedViewController.title, @"Second");

}

Answer 2

Here is what I do. Assume I have the DocumentsVC with manually triggered segue (DocumentsDetailVC) connected. Below is my setup and then I test for 1. the existence of the segue and then 2. I force the view controller (in my case I post a notification) to trigger its performSegueWithIdentifier and intercept the prepareForSegue Method to see if everything for the new view controller (DocumentsDetailVC) is set up. This includes method swizzling.

I have not that I use OCHamcrest/OCMockito for unit testing and that all my segues are named after the target view controller added by "Segue" ([self appDelegate] segueIdentifierForClass:[SomeClass class]]).

- (void)setUp
{
  [super setUp];

  _isPad = UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad;

  realPrepareForSegue = @selector(prepareForSegue:sender:);
  testPrepareForSegue = @selector(documentsBrowserTest_prepareForSegue:sender:);

  UIStoryboard *storyboard = nil;
  if (_isPad) {
    storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle:nil];
  }
  else {
    storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPad" bundle:nil];
  }
  UINavigationController *navController = [storyboard instantiateInitialViewController];
  self.sut = (DocumentsBrowserVC *)navController.topViewController;
  [self.sut view];
}


- (void)test_DocumentsDetailsVCSegueConnected
{
  if (_isPad == FALSE) {
    STAssertNoThrow([self.sut performSegueWithIdentifier:[[self appDelegate] segueIdentifierForClass:[DocumentsDetailVC class]] sender:self], @"DocumentsDetailVC should be connected");
  }
} 


- (void)test_providerDidSelectPathLevelObject_triggersDocumentsDetailsVCSegueSectionIdFile
{
  [DocumentsBrowserTest swapInstanceMethodsForClass:[DocumentsBrowserVC class]
                                                selector:realPrepareForSegue
                                             andSelector:testPrepareForSegue];

  [[NSNotificationCenter defaultCenter] addObserver:self.sut selector:@selector(providerDidSelectPathLevelObject:) name:ProviderDidSelectPathLevelObjectNotification object:nil];

  // when    
PathLevelObject *plo = self.pathLevelObjects[SectionIdFile][4];
NSDictionary *userInfo = @{OBJECT_KEY : plo , BROWSER_AREA_KEY : @(DocumentsFolder)};
[[NSNotificationCenter defaultCenter] postNotificationName:ProviderDidSelectPathLevelObjectNotification object:nil userInfo:userInfo];

  // then
  if (_isPad == FALSE) {
    assertThat(NSStringFromClass([objc_getAssociatedObject(self.sut, storyboardSegueKey) class]), is(equalTo(@"UIStoryboardPushSegue")));
    assertThatBool([[objc_getAssociatedObject(self.sut, storyboardSegueKey) destinationViewController] isKindOfClass:[DocumentsDetailVC class]], is(equalToBool(TRUE)));
    assertThat(objc_getAssociatedObject(self.sut, senderKey), is(equalTo(self.sut)));
  }
  else {
    assertThatInteger(self.sut.detailViewController.browsingArea, is(equalToInteger(DocumentsFolder)));
    assertThat(self.sut.detailViewController.pathLevelObject, is(equalTo(plo)));
  }


  [[NSNotificationCenter defaultCenter] removeObserver:self.sut];

  [DocumentsBrowserTest swapInstanceMethodsForClass:[DocumentsBrowserVC class]
                                                selector:realPrepareForSegue
                                             andSelector:testPrepareForSegue];
}