Ticket #12779: fib.cpp

#define BOOST_TEST_MODULE dataset_example68
#include <boost/test/included/unit_test.hpp>
#include <boost/test/data/test_case.hpp>
#include <boost/test/data/monomorphic.hpp>
#include <sstream>

namespace bdata = boost::unit_test::data;

// Dataset generating a Fibonacci sequence
class fibonacci_dataset {
public:
    // Samples type is int
    using sample=int;
    enum { arity = 1 };

    struct iterator {

        iterator() : a(1), b(1) {}

        int operator*() const   { return b; }
        void operator++()
        {
            a = a + b;
            std::swap(a, b);
        }
    private:
        int a;
        int b; // b is the output
    };

    fibonacci_dataset()             {}

    // size is infinite
    bdata::size_t   size() const    { return bdata::BOOST_TEST_DS_INFINITE_SIZE; }

    // iterator
    iterator        begin() const   { return iterator(); }
};

namespace boost { namespace unit_test { namespace data { namespace monomorphic {
  // registering fibonacci_dataset as a proper dataset
  template <>
  struct is_dataset<fibonacci_dataset> : boost::mpl::true_ {};
}}}}

// Creating a test-driven dataset 
// This does compile because the operator^ due to the second operand being in the correct namespace
BOOST_DATA_TEST_CASE(
    test1,
    fibonacci_dataset() ^ bdata::make( { 1, 2, 3, 5, 8, 13, 21, 35, 56 } ),
    fib_sample, exp)
{
      BOOST_TEST(fib_sample == exp);
}

// This does not compile because none of the operands is in the same namespace as the operator^
// It can be made working by declaring the fibonacci dataset within 
// namespace boost { namespace unit_test { namespace data { namespace monomorphic {
// However, that does not sound like a good solution.
BOOST_DATA_TEST_CASE(
    test2,
    fibonacci_dataset() ^ fibonacci_dataset(),
    fib_sample, exp)
{
      BOOST_TEST(fib_sample == exp);
}