Unit testing AFNetworking blocks can be tricky since SenTestingKit won't wait for the completion blocks to finish. Here's how I test my functions that deal with networking. Slightly adapted from https://gist.github.com/andrewroycarter/2254570

testFeatureFlags.m

/*
Testing the af.updateFeatureFlags method, which returns an AFJSONRequestOperation operation
*/

- (void) testFeatureFlags{
	dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
	
	[af.sharedHTTPClient enqueueBatchOfHTTPRequestOperations:@[af.updateFeatureFlags] progressBlock:nil completionBlock:^(NSArray *operations) {
		dispatch_semaphore_signal(semaphore);
	}];
	while (dispatch_semaphore_wait(semaphore, DISPATCH_TIME_NOW)) {
		[[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:10]];
	}
	STAssertFalse([af.featureFlags[@"fake_flag"] boolValue], @"Fake flag should be false");
	STAssertTrue([af.featureFlags[@"control_flag"] boolValue], @"Control flag should be true");
}