Use this Gist to test AFNetworking based network calls. Use the respective client to test the succes: for failure: blocks. Stub and expect to your hearts content.

AFTestSpec.m

//
//  AFTestSpec.m

@interface AlwaysSucceedClient : AFHTTPClient
@end
@implementation AlwaysSucceedClient
- (void)postPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *, id))success failure:(void (^)(AFHTTPRequestOperation *, NSError *))failure
{
    NSURLRequest *request = [self requestWithMethod:@"POST" path:path parameters:parameters];
  AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure];
    success(operation, operation.responseData);
}
- (void)getPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *, id))success failure:(void (^)(AFHTTPRequestOperation *, NSError *))failure
{
    NSURLRequest *request = [self requestWithMethod:@"GET" path:path parameters:parameters];
    AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure];
    success(operation, operation.responseData);
}
@end

@interface AlwaysFailClient : AFHTTPClient
@end
@implementation AlwaysFailClient

- (void)postPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *, id))success failure:(void (^)(AFHTTPRequestOperation *, NSError *))failure
{
    NSURLRequest *request = [self requestWithMethod:@"POST" path:path parameters:parameters];
	AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure];
    failure(operation, operation.error);
}

- (void)getPath:(NSString *)path parameters:(NSDictionary *)parameters success:(void (^)(AFHTTPRequestOperation *, id))success failure:(void (^)(AFHTTPRequestOperation *, NSError *))failure
{
    NSURLRequest *request = [self requestWithMethod:@"GET" path:path parameters:parameters];
    AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:success failure:failure];
    failure(operation, operation.error);
}

SPEC_BEGIN(NetworkInterfaceSpec)

describe(@"NetworkInterface", ^{
    __block NetworkInterface *network;
    __block AlwaysSucceedClient *succeed;
    __block AlwaysFailClient *fail;

    
    beforeEach(^{
        network = [NetworkInterface sharedInstance];
        
        NSURL *base = [NSURL URLWithString:@"http://www.baseurl.com"];
        succeed = (AlwaysSucceedClient *)[AlwaysSucceedClient clientWithBaseURL:base];
        fail = (AlwaysFailClient *)[AlwaysFailClient clientWithBaseURL:base];
        network.currentClient = succeed;
    });

    context(@"uploadData:", ^{
        beforeEach(^{
            [[ContactSync sharedInstance] stub:@selector(markContactsAsUploaded)];
        });
        
        it(@"should use the correct url", ^{
            [[succeed should] receive:@selector(postPath:parameters:success:failure:) withArguments:@"/api/v1/sync/contacts.json", [KWAny any], [KWAny any], [KWAny any]];
           
            [network uploadData:nil];
        });
        
        it(@"should use the correct data", ^{
            NSDictionary *fakeData = @{@"keyName": @"values"};
            [[succeed should] receive:@selector(postPath:parameters:success:failure:) withArguments:[KWAny any], fakeData, [KWAny any], [KWAny any]];
            
            [network uploadData:fakeData];
        });
        
        it(@"should update uploaded status on success", ^{
            [[[ContactSync sharedInstance] shouldEventually] receive:@selector(markContactsAsUploaded)];
            
            [network uploadData:nil];
        });
});