[Boost-users] [Test] Unit test for const suggestion.

Subject: [Boost-users] [Test] Unit test for const suggestion.
From: MA (anlmat_at_[hidden])
Date: 2010-09-22 17:53:35

Hi there!

I have been having some trouble unit testing const variables/types in my 
code. The problem I had was basically:

The compiler stops the compilation with an error if you try to change a 
const variable/type. Still you want to write a unit test that checks 
that the variable cannot be changed. So to check that the variable/type 
cannot be changed we can just check if the variable/type is const or 
not. By doing so we indirectly check that the variable/type cannot be 
changed.

So the suggestion for the Boost.Test library is to create a 
BOOST_CHECK_IS_CONST that works something like the code below but with 
the BOOST_CHECK_EQUAL syntax:

------
#include <iostream>
#include <boost/type_traits.hpp>

template<typename T >
bool isconst(T&, typename boost::enable_if<boost::is_const< T >,
  T >::type* = 0 )
{
   return true;
}

template< typename T >
bool isconst(T&, typename boost::disable_if<boost::is_const< T >,
T>::type* = 0 )
{
   return false;
}

int main()
{
   const int const_int = 0;
   int plain_int = 0;
   std::cout << isconst(const_int) << std::endl;
   std::cout << isconst(plain_int) << std::endl;
}
-----
By doing this you can check for const in a unit test like this:

BOOST_CHECK_EQUAL(isconst(const_int), true);

But it would be nicer with a BOOST_CHECK_IS_CONST.

Regards,
anlmat