//  Copyright Paul A. Bristow 2015.
//  Copyright Christopher Kormanyos 2015.
//  Distributed under the Boost Software License,
//  Version 1.0. (See accompanying file LICENSE_1_0.txt
//  or copy at http://www.boost.org/LICENSE_1_0.txt)

//! \file
/*!\brief Example of a Very Contrived Test for a list of types and their respective values.\n
It checks that the numeric_limits digits for the type is in accord with the expected value
that is contained in a type trait that can be selected by the test_type.\n

Method suggested by Gennadiy Rozental in email to Paul Bristow 3 Dec 2015.
*/

//! \sa http://www.boost.org/doc/libs/1_59_0/libs/test/doc/html/boost_test/tests_organization/test_cases/test_organization_templates.html#ref_BOOST_AUTO_TEST_CASE_TEMPLATE

#define BOOST_TEST_MODULE test_types_values
#define BOOST_LIB_DIAGNOSTIC

#include <boost/test/included/unit_test.hpp>
#include <boost/mpl/list.hpp> // for mpl::list

//#include <array>
#include <limits>
#include <iostream>
#include <type_traits>

// List of types to test.
typedef boost::mpl::list<char, short, int, long, long long> test_types;

template<typename T> struct ExpectedTDigits;
template<> struct ExpectedTDigits<char> { static const int value = 8 - 1; };
template<> struct ExpectedTDigits<short> { static const int value = 16 - 1; };
template<> struct ExpectedTDigits<int> { static  const int value = 32 - 1; };
template<> struct ExpectedTDigits<long> { static  const int value = 32 - 1; };
template<> struct ExpectedTDigits<long long > { static const int value = 64 - 1; };

// But a serious downside of this scheme is that it can't work with std::string or User-defined types.
// This is because these types can't be made static which is essential for this to work.
template<typename T> struct ExpectedTstring;
template<> struct ExpectedTstring<char> { static const std::string value = "char"; };
// Error	C2864	'ExpectedTstring<char>::value': a static data member with an in-class initializer must have non-volatile const integral type

BOOST_AUTO_TEST_CASE_TEMPLATE(my_test, T, test_types)
{
  // Test for a value that is same for all T - works fine.
  BOOST_CHECK_EQUAL(std::numeric_limits<T>::radix, 2);

  // Find the expected value for the type T.
  BOOST_CHECK_EQUAL(std::numeric_limits<T>::digits, ExpectedTDigits<T>::value);

} // BOOST_AUTO_TEST_CASE_TEMPLATE(my_test, T, test_types)


  /*
  Output:

  Running 5 test cases...
  *** No errors detected
  */