TARGET_OS_IPHONE and ApplicationTests

Why doesn't this code work when compiling an ApplicationTests unit test bundle?

#if TARGET_OS_IPHONE   #import <Foundation/Foundation.h>   #import <UIKit/UIKit.h>#else   #import <Cocoa/Cocoa.h>#endif

One of my dependencies has this check and compiles just fine in my main application bundles, but it tries to load <Cocoa/Cocoa.h> when compiling my ApplicationTests bundle. It's probably just my lack of understanding of Xcode, but I get nervous when my test bundles don't build. Any suggestions?