BowlingGameTest.m

#import "Game.h"
#import <SenTestingKit/SenTestingKit.h>


@interface BowlingGameTest : SenTestCase
{
    
}
@end


@implementation BowlingGameTest

- (void)testGutterGame {
    Game *game = [game init];
    
    for (int i = 0; i < 20; i++) {
        [game rollWithPinCount:0];
    }
    
    STAssertEquals([game score], 0, @"Gutter game should total 0");
}

@end

Game.h

#import <Foundation/Foundation.h>

@interface Game : NSObject

- (void)rollWithPinCount:(int)pins;
- (int)score;

@end

Game.m

#import "Game.h"

@implementation Game

- (void)rollWithPinCount:(int)pins {
    
}

- (int)score {
    return -1;
}

@end