faq.md

Frequently asked questions

STUB failure

mprotect

macOS (Mojave 10.14.6) macOS (Catalina 10.15.2) and later macOS mprotect fails, because max_prot.

   printf '\x07' | dd of=<executable> bs=1 seek=160 count=1 conv=notrunc

stack-protector

Compile option with -fstack-protector will cause STUB fail, remove this option, or add -fno-stack-protector option

unprotected commas

C/C++ preprocessor can't parse MACRO arguments which contains comma in '<>' correctly.

A solution is wrapping such argument with parentheses '()'.

write-strings/C2440 warning

C++ string literals are const

In C, the type of a string literal is array of char, but in C++, it's array of const char.

char* s1 = "test"; // Warning
const char* s2 = "test"; // OK

macro conflict

If product code already defined SUITE Case..., define H2_NO_SUITE and using H2SUITE instead.

private member method accessibility

In order to access/STUB/MOCK class private member function successfully. https://stackoverflow.com/questions/860923/unit-testing-with-fno-access-control

solution 1: substituted by MACRO

private protected token is substituted with public using MACRO definition by default in h2unit.h/hpp.

H2_NO_Redefine_private is used to disable above substitution.

private protected substituted with public conflict with c++17 include

solution 2: compiler option

-fno-access-control GCC/clang compiler option.

clang 11 on linux platform has a bug, -fno-access-control -fno-no-access-control not works.

static function accessibility

static function is unaccessible outside of source file. In order to STUB/MOCK such function successfully, there are two solutions:

solution 1: include source file in test file

   // test_module.cpp
   #include "h2unit.h"
   #include "module.c/cpp"
   CASE(a test)
   {
      ...
   }

solution 2: STUB/MOCK by function string name

   static int a_static_function(char * str) {
      ...
   }

   CASE(a test)
   {
      STUB("a_static_function", fake_function);
      MOCK("a_static_function", int(char *)).Once().Return(11);
   }

If function is overload function, arguments type should specified, i.e. C++ demangled function name.

   CASE(a test)
   {
      STUB("a_static_function(char*)", fake_function);
      MOCK("a_static_function(char*)", int(char *)).Once().Return(11);
   }

nm --demangle ./a.out | grep a_static_function can find out demangled function name.

STUB in dynamic library

   LD_BIND_NOW=1 ./a.out 
   gcc --Wl,z,now

backtrace symbol name

add linker option -rdynamic

Variadic parameter function can't MOCK

use STUB with separate fake function instead

sqrt() in math.h can't be STUB/MOCK

compiler insert sqrtsd ASM instruction directly instead of function call