Re: [boost] Using BOOST_AUTO_TEST_CASE_TEMPLATE but passing a list of test values too

-----Original Message----- From: Boost [mailto:boost-bounces@lists.boost.org] On Behalf Of Paul A. Bristow Sent: 02 December 2015 10:56 To: boost@lists.boost.org Subject: [boost] Using BOOST_AUTO_TEST_CASE_TEMPLATE but passing a list of test values too

I want to test a (quite large) variety of user-defined types using Boost.Test.

As a very contrived example, suppose I wanted to check numeric_limits digits for integer types

I'd like to avoid a tediously long list like this

BOOST_CHECK_EQUAL(std::numeric_limits<char>::digits, 8); BOOST_CHECK_EQUAL(std::numeric_limits<char>::digits, 16); BOOST_CHECK_EQUAL(std::numeric_limits<char>::digits, 32); ...

and follow the example of

BOOST_AUTO_TEST_CASE_TEMPLATE

but allow a test value to be passed too,

something like this:

typedef boost::mpl::list test_types;

and a list of test values, perhaps like this

typedef list_c test_values;

(However it would be *far* more useful to be able to test strings and floats and User-defined types too).

BOOST_AUTO_TEST_CASE_TEMPLATE_????(digits_test, T, test_types, test_values) { BOOST_CHECK_EQUAL(std::numeric_limits<T>::digits, test_values); }

Has any Macro Guru produced a BOOST_AUTO_TEST_CASE_TEMPLATE_? that includes a list of test values?

After some discussion with Gennadiy Rozental (Boost.Test author) , the answer is that he is working on a dataset system that would permit this (but not imminent). Two possible workarounds: 1 Gennadiy suggested using // List of types to test. typedef boost::mpl::list test_types; // Values that types should have. 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) { // Find the expected value for the type T. BOOST_CHECK_EQUAL(std::numeric_limits<T>::digits, ExpectedTDigits<T>::value); } so it works OK with my very contrived example, but not for all types (for my application a killer as need check against UDT values). 2 Playing dirty and using a global indexer to containers (array, vector..) of the values to check against. int index = 0; // Global so that can be accessed by digits_test // Container for expected values of std::numeric_limits<T>::digits for the types above. // It's size must match the size of the list of types to test. std::array type_values { { 8-1, 16-1, 32-1, 32-1, 64-1 } }; // Similarly OK for an array of any value type, including UDT, for example //std::array type_strings { { "char", "short", "int", "long", "long long" } }; //std::array type_std_strings { { "char", "short", "int", "long", "long long" } }; template <typename T> void digits_test() { int digits = type_values[index]; // 8 if T == char, 16 if T == short, 32 if T == int ... BOOST_CHECK_EQUAL(std::numeric_limits<T>::digits, digits); // Test for corresponding value. // Possibly check against other items like type_strings[index] ... index++; // ready for next type. return; } // void digits_test() BOOST_AUTO_TEST_CASE_TEMPLATE(my_test, T, test_types) { // Find the expected value for the type T from the array type_values. digits_test<T>(); } // BOOST_AUTO_TEST_CASE_TEMPLATE(my_test, T, test_types) Two working examples attached in case anyone wants to solve the same sort of problem. Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 (0) 1539 561830