Link error while building a unit test target
Unit TestingXcode4Linker ErrorsOcunitUnit Testing Problem Overview
I have a XCode4 / iOS project with a regular target and unit test target. Everything works fine, except when I try to #import one of my classes in my test class and try to use it. If I try to build the unit test target, I get the following link error:
Undefined symbols for architecture i386:
"_OBJC_CLASS_$_FRRCategory", referenced from:
objc-class-ref in CategoryTests.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status
In CategoryTests.m I'm importing the header file in this way:
#import "../todoro/FRRCategory.h"
What am I doing wrong?
Unit Testing Solutions
Solution 1 - Unit Testing
Follow the instructions here. It doesn't require you to add any files to compile sources.
I first missed that "Symbols Hidden by Default=NO" should be for your app target, not test target.
It worked for me anyway (tm).
Solution 2 - Unit Testing
Make sure that the FRRCategory source file has been added to your Compile Sources for your unit test target.
Xcode 4:
Project Navigator -> "[Project Name]" -> Under Targets select your unit test target -> Build Phases -> Expand Compile Sources -> Click + at bottom of Compile sources and add the correct source file.
Solution 3 - Unit Testing
Another gotcha that you may hit is if your unit test is using C functions (or similar) that aren't used in the actual app.
This may be restricted to having a sub-project. In my case
- App
- Sub-project
- A C library embedded (i.e. .c and .h files compiled directly inside)
- Sub-project
My unit test used a few of the C functions that were not used anywhere else, and these were stripped from the app binary (NOT from the sub project's .a file).
The fix is to
- turn off "Dead Code Stripping" for the app's Debug build.* and
- make sure your unit tests are using Debug and not Release, in the Scheme settings.
(* don't do this to the release configs as it'll bloat the app with code that is never called).
Solution 4 - Unit Testing
You should only refer to a folder inside your import if your file is inside a framework. Otherwise, once you added your file to the project, simply do #import "FRRCategory.h". Well, unless you did something weird with your Header Search Paths.
Solution 5 - Unit Testing
In my case, the host app was "Custom". I had to change it to an iOS target and set "Allow testing Host Application APIs". You can find it on the General tab of your test target.
