Linker error with Cedar tests

Question

To teach myself Objective C and Cocoa, I want to write a diff tool. I'm using the Cedar testing framework, and I can't for the life of me get my test bundle to build.

XCode doesn't present me with any warnings until I hit 'run tests', when the linker throws its toys out of the pram. The exact error I'm getting is:

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_LongestCommonSubsequence", referenced from:
    objc-class-ref in LowestCommonSubsequenceTests.o
    (maybe you meant: _OBJC_CLASS_$_LowestCommonSubsequenceTests)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Here's the folder structure of my project:

Project: Diff
  Diff
    AppDelegate.h
    AppDelegate.m
    MainMenu.xib
    LowestCommonSubsequence.h
    LowestCommonSubsequence.m
    Supporting Files
  DiffTests
    LowestCommonSubsequenceTests.mm
    Rakefile
    Cedar.framework
    Supporting Files
  Frameworks
  Products

Here is my first test in LowestCommonSubsequenceTests.mm, which I paraphrased from the example on the Cedar wiki:

#import "LowestCommonSubsequence.h"

using namespace Cedar::Matchers;
using namespace Cedar::Doubles;

SPEC_BEGIN(LowestCommonSubsequenceTests)

describe(@"When both input arrays are empty", ^{

    it(@"should return an empty array", ^{
        [LowestCommonSubsequence ofLeftArray:@[] andRightArray:@[]] should be_empty;
    });

});

SPEC_END

Here is LowestCommonSubsequence.h:

#import <Foundation/Foundation.h>

@interface LowestCommonSubsequence : NSObject

+ (NSArray *)ofLeftArray:(NSArray *)left andRightArray:(NSArray *)right;

@end

And here is LowestCommonSubsequence.m:

#import "LowestCommonSubsequence.h"

@implementation LowestCommonSubsequence

+ (NSArray *)ofLeftArray:(NSArray *)left andRightArray:(NSArray *)right
{
    return @[];
}

@end

Do I have my #import statement wrong? Is the folder structure incorrect? Did I set up my build targets wrong?

I found my problem on the Cedar wiki, which suggested running in Debug mode, but as far as I can make out, everything is already set up to run in Debug mode with the default settings.

Apologies if this is an idiotic question. This is literally the first Objective C code I've ever written.

Answer 1

I fixed the issue by changing the Build Settings for the test bundle:

Bundle Loader: $(BUILT_PRODUCTS_DIR)/<App Name>.app/Contents/MacOS/<App Name> Test Host: $(BUNDLE_LOADER)