Question

I know that the whole point of singleton is to instantiate 1 instance of the onject and reuse it, but when it comes to unit testing I want to be able to renew the singleton object before every test.

I tried to use a category to access the singleton object and release it but It’s not accessible by categories any idea what’s the best way to achieve this?

@implementation SingletonClass

static SingletonClass *singleton;

+ (SingletonClass*)sharedInstance
{
   if (!singleton)
   {
      singleton = [[SingletonClass alloc] init];
   }
   return singleton;
}

@end

.

@implementation SingletonClass(Unit Testing Additions)

+ (void)killInstance
{
   // I get an error here and I cannot access the singleton Object
   [singleton release], singleton = nil;
}

@end

Answer 1

I’m not sure whether this will work, but maybe you could just override the sharedInstance class method and manage the singleton yourself:

@implementation SingletonClass (Unit Testing Additions)

static SingletonClass *myVeryOwnSharedInstance;

+ (SingletonClass *) sharedInstance
{
    if (!myVeryOwnSharedInstance)
        myVeryOwnSharedInstance = [[self alloc] init];
    return myVeryOwnSharedInstance;
}

+ (void) killInstance
{
    [myVeryOwnSharedInstance release];
    // if release is overridden to do no-op, maybe just invoke -dealloc directly
    myVeryOwnSharedInstance = nil;
}

@end