XCTest and CoreData

Question

I am trying to Unit test my model in Xcode 5 by using the XCTest classes and methods.

Because my model classes inherit of managedObject, I can't just instantiate (alloc/init) them and call the getters and setters or the methods I need to test. I need to create them by using the NSEntityDescription and use a managedObjectContext.

That is with this point that I get troubles. I don't know where and how to create the managedObjectContext for unit tests purpose.

If anyone has some advice or code examples, it will be very helpful. Thanks.

Answer 1

I use an in memory store to for my unit tests and create all the entities within that.

This class method can be placed in TestsHelper.m

+ (NSManagedObjectContext *)managedObjectContextForTests {
    static NSManagedObjectModel *model = nil;
    if (!model) {
        model = [NSManagedObjectModel mergedModelFromBundles:[NSBundle allBundles]];
    }

    NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:model];
    NSPersistentStore *store = [psc addPersistentStoreWithType:NSInMemoryStoreType configuration:nil URL:nil options:nil error:nil];
    NSAssert(store, @"Should have a store by now");

    NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    moc.persistentStoreCoordinator = psc;

    return moc;
}

This works for me because I use Dependency Injection to pass my moc around rather than using a singleton.