CODEWITHSUNDEEP
cunit-testing
Colin Harker
Colin Harker

Reputation: 43

Custom #define macro for unit testing

I have a function that is returning the condition of a macro, and for unit testing I want to be able to determine what this macros value is.

Currently I have,

#define READ_PORT ReadingPortStatus(SOME_OTHER_CONDITION)

#ifdef UNIT_TEST
bool READ_PORT_flag_UT;
#endif

void ReturnPortCondition()
{
#ifdef UNIT_TEST
#undef READ_PORT
    if (READ_PORT_flag_UT)
    {
        #define READ_PORT 1
    }
    else
    {
        #define READ_PORT 0
    }
#endif

    if (READ_PORT)
    {
        return(GOOD_READ);
    }
    else
    {
        return(BAD_READ);
    }
}

And in my unit test file I would use it as follows,

extern READ_PORT_flag_UT;

READ_PORT_flag_UT = true // Because I want ReturnPortCondition() to return true
bool result = ReturnPortCondition();

However, it is not working as I expect, it is only returning the last define of the port, which in this case is 0. the if else statements are not working in this context.

Upvotes: 0

Views: 1554

Answers (1)

Kevin
Kevin

Reputation: 7324

Macros are entirely compile time. You can't change a #define based on a runtime condition.

What you can do instead is re-define READ_PORT to be your READ_PORT_flag_UT variable instead of a function call. That way if UNIT_TEST is defined any use of READ_PORT will use that variable. If UNIT_TEST isn't defined READ_PORT will be the function call.

#ifdef UNIT_TEST
bool READ_PORT_flag_UT;
#define READ_PORT READ_PORT_flag_UT
#else
#define READ_PORT ReadingPortStatus(SOME_OTHER_CONDITION)
#endif

void ReturnPortCondition()
{
    if (READ_PORT)
    {
        return(GOOD_READ);
    }
    else
    {
        return(BAD_READ);
    }
}

Upvotes: 2

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