test tree is empty when run the example of boost 1.80

[kwarehit]

hi all, The following code was copied from https://www.boost.org/doc/libs/1_80_0/libs/test/doc/html/boost_test/runtime_config/custom_command_line_arguments.html, but output results is "test tree is empty" when run it by used command line "--log_level=all -- --test-file test_file.txt": Test setup error: test tree is empty The contents of test_file.txt:

10.2 30.4
10.3 30.2
15.987984 15.9992
15.997984 15.9962

code is here:

#define BOOST_TEST_MODULE runtime_configuration4

#include <boost/test/included/unit_test.hpp>
#include <boost/test/data/test_case.hpp>

#include <iostream>
#include <functional>
#include <sstream>
#include <fstream>

// this dataset loads a file that contains a list of strings
// this list is used to create a dataset test case.
class file_dataset
{
private:
    std::string m_filename;
    std::size_t m_line_start;
    std::size_t m_line_end;

public:
    static const int arity = 2;

public:
    file_dataset(std::size_t line_start = 0, std::size_t line_end = std::size_t(-1))
    : m_line_start(line_start)
    , m_line_end(line_end)
    {
      int argc = boost::unit_test::framework::master_test_suite().argc;
      char** argv = boost::unit_test::framework::master_test_suite().argv;

      if(argc != 3)
        throw std::logic_error("Incorrect number of arguments");
      if(std::string(argv[1]) != "--test-file")
        throw std::logic_error("First argument != '--test-file'");
      if(!(m_line_start < std::size_t(-1)))
        throw std::logic_error("Incorrect line start/end");

      m_filename = argv[2];

      std::ifstream file(m_filename);
      if(!file.is_open())
        throw std::logic_error("Cannot open the file '" + m_filename + "'");
      std::size_t nb_lines = std::count_if(
        std::istreambuf_iterator<char>(file),
        std::istreambuf_iterator<char>(),
        [](char c){ return c == '\n';});

      m_line_end = (std::min)(nb_lines, m_line_end);
      if(!(m_line_start <= m_line_end))
        throw std::logic_error("Incorrect line start/end");
    }

    struct iterator {
        iterator(std::string const& filename, std::size_t line_start)
        : file(filename, std::ios::binary) {
          if(!file.is_open())
            throw std::runtime_error("Cannot open the file");
          for(std::size_t i = 0; i < line_start; i++) {
            getline(file, m_current_line);
          }
        }

        auto operator*() const -> std::tuple<float, float> {
          float a, b;
          std::istringstream istr(m_current_line);
          istr >> a >> b;
          return std::tuple<float, float>(a, b);
        }

        void operator++() {
          getline(file, m_current_line);
        }
    private:
        std::ifstream file;
        std::string m_current_line;
    };

    // size of the DS
    boost::unit_test::data::size_t size() const {
      return m_line_end - m_line_start;
    }

    // iterator over the lines of the file
    iterator begin() const   {
      return iterator(m_filename, m_line_start);
    }
};

namespace boost { namespace unit_test { namespace data {

namespace monomorphic {
  template <>
  struct is_dataset<file_dataset> : boost::mpl::true_ {};
}
}}}

BOOST_DATA_TEST_CASE(command_line_test_file,
    boost::unit_test::data::make_delayed<file_dataset>( 3, 10 ),
    input, expected) {
    BOOST_TEST(input <= expected);
}

Compiler is: vs2022.17.3 which default C++ standard is 14, boost version is 1.80 Looking forward to your reply, thanks

[kwarehit]

I found root cause is that calling of boost::unit_test::data::make_delayed dose not set value to m_dataset which is inside member of class boost::unit_test::data::monomorphic::delayed_dataset, so the workflow will not do generate test_unit, the key code snippet is there:

template<typename DataSet, typename Action>
inline typename std::enable_if<monomorphic::is_dataset<DataSet>::value,void>::type
for_each_sample( DataSet const &    samples,
                 Action const&      act,
                 data::size_t       number_of_samples = BOOST_TEST_DS_INFINITE_SIZE )
{
    data::size_t size = (std::min)( samples.size(), number_of_samples );
    .....
}

in above code snippet, the variable size is 0, so there is no test case to be run

I think member function file_dataset::size() on example should be call in above parameter samples

[kwarehit]

Final, the reason is content in the test_file.txt, because these are absence of new character '\n', if add a new line, the case will be run.

10.2 30.4
10.3 30.2
15.987984 15.9992
15.997984 15.9962
<= this is a new line

I think the error prompt of boost.test should be more details but not generic message "Test setup error: test tree is empty", Is this room for improvement?

[raffienficiaud]

Thanks for this investigation!