How do I use "unity" to unit test C code on Mac (Lion)?

Question

Let me start out by saying that I'm not a C developer and I know very little about actually writing real world C code. I've been doing some research to find a xUnit framework that I can use to write tests for C code and based on what I've found it seems like Unity is the one that I want to go with. It seems simple enough, but I really just don't know what to do after I download the zip file from Unity's website. It doesn't seem to have the normal configure/make/make install, and if it did, I'm not sure that is what I should be using anyway. It does, however, ship with some rake tasks, but none of those seemed to be any kind of "install" task. As a last resort I tried to just copy the 3 source files in with my code (which I really hope is not the right thing to do), but when I try that I get an error trying to compile my c file with gcc, but I think this should be working. Here is my set up:

src/
  mycode.c
  unity.c
  unity.h
  unity_internals.h

Here is the source for mycode.c

/* mycode.c */
#include "unity.h"

void test_sample(void)
{
    TEST_ASSERT_EQUAL_INT(0, 0);
}

When I run gcc mycode.c I get:

Undefined symbols for architecture x86_64:
  "_main", referenced from:
      start in crt1.10.6.o
  "_UnityAssertEqualNumber", referenced from:
      _test_sample in ccyHByv6.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

(I get a similar error when I try to compile unity.c with gcc). Which I assume means that the code that ships with unity requires a different compiler than what I have which is:

i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.9.00)

or that maybe unity is not compatible with a 64 bit processor... (I'm running on Mac OS 10.7.3 with a 2.4 GHz Intel Core 2 Duo processor - another thing that may or may not be relavent is that I've got XCode Version 4.3 (4E109) and also Command Line Tools for XCode) At this point I'm just grasping at straws and I'm in way over my head.

My question is, what is the correct process to go through to take a 3rd party C library, such as Unity, and make it available to my C code? Do I need to install something like in Python or Ruby or add something to my path like in Java or something else? Shouldn't just dropping unity's code in with mine work? Am I doing something wrong or is Unity or both? I really just want to be able to test drive C code using Unity. Any help would be greatly appreciated. Thanks in advance!

Answer 1

First, try 'gcc *.c -o mytest'. This will compile all of the C source files into object files, and then link them together into the binary 'mytest'. Keep in mind that all C source files have to be compiled to object files before they can be linked together. (A library is just a bunch of packaged object files.)

If you had a unity library installed in /usr/lib, you could do something like 'gcc mycode.c -lunity -o mytest'. If you had a unity library sitting in the current directory, you might do 'gcc mycode.c ./unity.a -o mytest'. This tells the compiler to look for a file named 'unity.a' in the current directory. Some libraries build .so files ('shared object' files, similar to DLLs in Windows). Replacing 'unity.a' with 'unity.so' should work if that is the case. (I'm assuming a Unix/Linux environment here.)

As an alternative to Unity, look at Google Test, which can be used with C code. I know it is supported on the Mac as well. The primary benefit is a large and active community. More information on Google Test from another SO question: Is Google Test OK for testing C code?

Answer 2

I figured out my problem. It turns out that unity requires you to define a setup and a teardown function and if you do not, you will get errors similar to the one that I was running into.