Problem and solution of TDD in C

1.Introduction

Today, Automatic unit test using xUnit is popular in Object-Oriented language(Java,C++,C# etc.). But it is not popular in C.

C is major language for development of embedded software. I think that TDD is very useful for Embedded software because bug fix is difficult after release.

I will explain problem and solution of TDD in C.

2.Framework

 I used CUnit for Mr.Ando for trying this method. CUnit for Mr.Ando is simple test framework for C.

This method doesn't depend on this framework. You can use other framework in C. ex. CUnit

3.Unit test in C

Target of unit test in OO language is a class but it is a function in C. In OO language, Mock object is used when target class call other class's method.

In C, Stub is used when target function call other function.

4.Problem of automatic unit test in C

I faced following problem when I tried automatic unit test using test-framework.

(1)Conflict of real and stub Real function's name comes into conflict stub's name.

(2) Conflict of stub to each other Stub's name comes into conflict stub's name for other function's test.

 Compile error occur in these cases. We can't avoid it because we can't use namespace in C.

 5.Solution for these problems

I will explain solution for conflicts. You can avoid conflicts by the following process.

(1)Define target function as another name in test project.

#ifdef TEST func_true() #else func() { .... .... }

You can define as another name in test project by using '#ifdef'.

(2)Define following functions.

Function’s pointer

SetFunctionPointer(fp)
{
  Function’s pointer=fp;
}
Function()
{
  Function’s pointer();
}