Basic unit test and C, how do I get started?

Question

After reading quite some threads here at StackOverflow, I have come to the conclusion that I should adopt to some form of test driven development/unit test (or at least explore the area).

And since we are talking about c code under Linux, I decided to give check a try (I don't know if this is the right choice but if it's no good I can always try something else later on).

But since this concept of unit test and unit test frameworks is totally new to me, I started out to do some unit test on a really small test code (but I was totally lost anyway and it felt like I was missing something).

This is what I have done so far, I created the following file:

• main.c, a main that only calls a function called my_pow and prints the result.
• my_pow.c, contains the function my_pow.
• my_pow.h
• my_pow_test.c, I figured that I should place the unit code for the my_pow function here.

(So the "normal program" is the main.c, my_pow.c and my_pow.h.)

This is my_pow.c

#include "my_pow.h"
int my_pow(int a, int b)
{
    return (a*b);
}

Then I figured that in my_pow_test.c I put something like this:

#include <check.h>
#include "my_pow.h"

START_TEST (test_my_pow)
{
    /* unit test code */
}
END_TEST

//do I need some sort off main here that calls test_my_pow?

This is basically the same as in the check manual chapter 3.1, but still not....

Could someone please push me in the right direction?

Thanks Johan

---

Update: No reason why I tried to use check I just thought I should start somewhere, maybe CUnit is a better choice (I think I would try that as well and then make a educated choice).

Update: Thanks @philippe for indirectly pointing out that the on-line documentation is only half of the truth, the example code that clarifies what the documentation talks about was already installed with the check package. In the Ubuntu case /usr/share/doc/check/example/tests/

Update: The code example was created so that you started out by looking at his first version, then the second one etc etc. So that you could follow how he creates a very basic test case/code from nothing up to something that is useful in a traditional TTD way.

And since my code was broken and I wanted the unit test to prove this, I cheated a little and tested against the real pow function. Something like this:

START_TEST (test_my_pow1)
{
    int resultat = my_pow(3,3);
    int math     = pow(3,3);
    fail_unless ( resultat == math,
           "Error on 3^3 != %d (%d)",math, resultat);
}

However in the future I will not reproduce what is already in the stdlibs :-)

---

Related:

• Unit Testing C Code
• How to test C Code
• Unit Testing Frameworks for C
• Testing Frameworks for C
• Basic unit test and C, how do I get started?

taken from searching [c] [unit-testing].

Answer 1

You created a first test case. Now you need to create a test suite (a group of test cases) and a runner.

I would recommend you try to compile their example first to validate your environment, although their documentation introduces new code via diff (source patch) which I do not find very convenient.

---

If ever you decide to try with another framework (minunit came to my mind immediately), I can point you to a "tutorial".