spec.m

#import <Foundation/Foundation.h>
#import <Block.h>

typedef BOOL (^SpecTestBlock)(NSObject *obj);
typedef NSString *(^SpecErrorBlock)(NSObject *obj);

@interface SpecMatcher : NSObject {
   SpecTestBlock testBlock;

   SpecErrorBlock errorBlock;
   SpecErrorBlock shouldNotErrorBlock;
}

+ (SpecMatcher*)matcherWithTest:(SpecTestBlock)test
			  error:(SpecErrorBlock)error
		       errorNot:(SpecErrorBlock)notError;

- (id)initWithTest:(SpecTestBlock)test
	     error:(SpecErrorBlock)error
	  errorNot:(SpecErrorBlock)notError;

- (BOOL)executeWith:(NSObject*)object;

- (NSString*)errorFor:(NSObject*)object;
- (NSString*)shouldNotErrorFor:(NSObject*)object;

- (void)dealloc;

@end

@implementation SpecMatcher

+ (SpecMatcher*)matcherWithTest:(SpecTestBlock)test
			  error:(SpecErrorBlock)error
		       errorNot:(SpecErrorBlock)notError {
   return [[[self alloc] initWithTest:test error:error errorNot:notError]
	     autorelease];
}

- (id)initWithTest:(SpecTestBlock)test
	     error:(SpecErrorBlock)error
	  errorNot:(SpecErrorBlock)notError {
   if (self = [super init]) {
      testBlock           = Block_copy(test);
      errorBlock          = Block_copy(error);
      shouldNotErrorBlock = Block_copy(notError);
   }
   return self;
}

- (BOOL)executeWith:(NSObject*)object {
   return testBlock(object);
}

- (NSString*)errorFor:(NSObject*)object {
   return errorBlock(object);
}

- (NSString*)shouldNotErrorFor:(NSObject*)object {
   return shouldNotErrorBlock(object);
}

- (void)dealloc {
   Block_release(testBlock);

   Block_release(errorBlock);
   Block_release(shouldNotErrorBlock);

   [super dealloc];
}

@end

@interface NSObject (Spec)
- (void)should:(SpecMatcher*)matcher;
- (void)shouldNot:(SpecMatcher*)matcher;
@end

@implementation NSObject (Spec)

- (void)should:(SpecMatcher*)matcher {
   BOOL res = [matcher executeWith:self];
   NSAssert(res, [matcher errorFor:self]);
}

- (void)shouldNot:(SpecMatcher*)matcher {
   BOOL res = [matcher executeWith:self];
   NSAssert(!res, [matcher shouldNotErrorFor:self]);
}

@end

SpecMatcher *beEqualTo(NSObject *arg) {
   return [SpecMatcher matcherWithTest:^(NSObject *obj) {
	 return [obj isEqual:arg];
      }
     error:^(NSObject *obj) {
	 return [NSString stringWithFormat:@"%@ should be equal to %@",
			  obj, arg];
      }
     errorNot:^(NSObject *obj) {
	 return [NSString stringWithFormat:@"%@ should not be equal to %@",
			  obj, arg];
      }];
}

int main(int argc, char *argv[]) {
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
   NSNumber *object = [NSNumber numberWithInt:30];
   [object should:beEqualTo([NSNumber numberWithInt:29])];
   [pool drain];

   return 0;
}