How to Test to cover all branchs of function casting char array to struct use Google test C language

问题

I am practicing google test C. I have a bit of confusion when writing a test case for function_1 function.

typedef struct
{
    int a;          //4 byte
    char b;         //1 byte
    char c;         //1 byte
    char d;         //1 byte
    char arr[3];    //3 byte
}ABCXYZ;

static void function_1(char *abc)
{
    if (abc != null)
    {
    ABCXYZ *name =(ABCXYZ *)(abc + 4);
    if (name->b == 1) 
        printf("ONE");
    else if (name->b == 2)
        printf("TWO");
    else 
        printf("OTHER");
    }
    else
    {
        printf("INVALID");
    }
}

I have written test case like this:

TEST(Test_function_1,abc_null)
{
    function_1(null);
}
TEST(Test_function_1,one)
{
    char arr[10]={1,0,0,0,0,0,0,0,0,0}; 
    function_1(arr);
}
TEST(Test_function_1,two)
{
    char arr[10]={2,0,0,0,0,0,0,0,0,0};
    function_1(arr);
}
TEST(Test_function_1,other)
{
    char arr[10]={3,0,0,0,0,0,0,0,0,0};
    function_1(arr);
}

But when I check result and report coverage html, it is not cover all branchs in function. How I can change test case to cover entire branchs ?

回答1:

It's not about the test cases but your function has a problem.

This line of code ABCXYZ *name =(ABCXYZ *)(abc + 4); does not help you to pass the value of the first element of the array into the field b of struct name.

So name->b always has some random value and in these cases the value are happened to be different to 1 and 2 so you got the else branch.

You need to allocate memory for name and then assign value of abc[0] to the field b:

    ABCXYZ *name = (ABCXYZ *) malloc (sizeof (ABCXYZ)); 
    name->b = abc[0];

p/s: This function is wierd though.

来源：https://stackoverflow.com/questions/59509615/how-to-test-to-cover-all-branchs-of-function-casting-char-array-to-struct-use-go

标签

googletest