cmockery | lightweight library to simplify and generalize the process | Unit Testing library

funcA() calls the function. You want a pointer to the function, which is funcA or &funcA (does not make a difference which one you use: read here).

Also you want to compare the value saved in FunctionPtr with the address of funcA. You do not want to compare the memory where FunctionPtr points to with the function.

So instead of assert_memory_equal( FunctionPtr, funcA(), sizeof( funcA() ) ); I would use assert(FunctionPtr == funcA);

You wrote in your comment that you are using assert_int_equal now. Note that both values are not int, so if the macro uses printf with %d (or similar) in an error case you are invoking undefined behaviour.

I want to assign value to updateMode so that it is not equal to SYSTEM_CAL_CONFIG

If updateMode depends on value, which you get from another function and you want to control it during the test, then you should create a test double of that function. Here is a good answer explaining mocks in particular. If it is calculated entirely inside checkSystem, then test driver should not modify it, as its purpose is only to check the overall result.

checkSystem.c