Unit Testing in Xcode, does it run the app?

Question

I\'m running into a strange problem that I haven\'t run into before.

When you do cmd+U to run your Unit Tests (OCUnit for example) does it actually call the main.m,

Answer 1

Here's a variation of Sulthan's answer that uses XCTest, which is the default for test classes generated by XCode 5.

int main(int argc, char * argv[])
{
    @autoreleasepool {
        BOOL runningTests = NSClassFromString(@"XCTestCase") != nil;
        if(!runningTests)
        {
            return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
        }
        else
        {
            return UIApplicationMain(argc, argv, nil, @"TestAppDelegate");
        }
    }
}

This goes into main.m, which should be under Supporting Files in a standard project layout.

Then in your tests directory add:

TestAppDelegate.h

#import <Foundation/Foundation.h>

@interface TestAppDelegate : NSObject<UIApplicationDelegate>
@end

TestAppDelegate.m

#import "TestAppDelegate.h"

@implementation TestAppDelegate
@end

Answer 2

In Swift, I prefere to bypass a normal execution path inside application: didFinishLaunchingWithOptions:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    guard normalExecutionPath() else {
        window = nil
        return false
    }

    // regular setup

    return true
}

private func normalExecutionPath() -> Bool {
    return NSClassFromString("XCTestCase") == nil
}

Code inside guard will remove any views created from storyboard.

Answer 3

Yes, your test target will have a target dependency to the app target, so the app target will be built when you press Cmd+U or Cmd+Shift+U.

Answer 4

The application is actually run but there is a trick you can use to prevent it from running.

int main(int argc, char* argv[]) {
    int returnValue;

    @autoreleasepool {
        BOOL inTests = (NSClassFromString(@"SenTestCase") != nil
                     || NSClassFromString(@"XCTest") != nil);    

        if (inTests) {
            //use a special empty delegate when we are inside the tests
            returnValue = UIApplicationMain(argc, argv, nil, @"TestsAppDelegate");
        }
        else {
            //use the normal delegate 
            returnValue = UIApplicationMain(argc, argv, nil, @"AppDelegate");
        }
    }

    return returnValue;
}

Answer 5

If you're using Swift (you probably don't have a main.c), you have to do these steps :

1: remove @UIApplicationMain in AppDelegate.swift

2: Create an empty TestingAppDelegate.swift

import UIKit
class TestingAppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
}

3: Create a file called main.swift :

import Foundation
import UIKit

let isRunningTests = NSClassFromString("XCTestCase") != nil

if isRunningTests {
   UIApplicationMain(C_ARGC, C_ARGV, nil, NSStringFromClass(TestingAppDelegate))
} else {
   UIApplicationMain(C_ARGC, C_ARGV, nil, NSStringFromClass(AppDelegate))
}

Answer 6

Excellent answers above that suggest dynamically changing the application delegate at run time.

The small modification I make is to detect a unit test run by querying NSProcessInfo. The advantage is that you don't need to have a class that can be detected to see if unit tests are running.

    int main(int argc, char * argv[])
    {
        // Put your App delegate class here.
        const Class appDelegateClass = [ATAppDelegate class];

        NSDictionary *const environmentDictionary =
        [[NSProcessInfo processInfo] environment];

        const BOOL runningUnitTests =
        environmentDictionary[@"XCInjectBundleInto"] != nil;

        NSString *delegateName = 
        runningUnitTests ? nil : NSStringFromClass(appDelegateClass);

        @autoreleasepool {
            return UIApplicationMain(argc, argv, nil, delegateName);
        }
    }

The @"XCInjectBundleInto" property in environmentDictionary is the path to your unit tests bundle and is set up by Xcode.