[Boost-users] Boost.Test BOOST_TEST/BOOST_REQUIRE_MESSAGE message arg problems

Subject: [Boost-users] Boost.Test BOOST_TEST/BOOST_REQUIRE_MESSAGE message arg problems
From: Olaf Peter (ope-devel_at_[hidden])
Date: 2018-05-20 17:42:47

Hello Boost Users,

for my project I'm testing using BOOST_AUTO_TEST_SUITE and data driven 
test sets (BOOST_DATA_TEST_CASE). The goal is to check the proper 
working of a parser by checking success as such and compare the result 
with a "expected" data (string) vector. In case of parse error, I want 
to write the captured cout/cerr by boost.test into a file. In case of 
compare error the parsed result also shall be written to a file. The 
fragments show the concept/current state:

namespace x3_test { // aka utils ....

/* [Detect if boost test case failed](
 Â * 
https://stackoverflow.com/questions/18466857/detect-if-boost-test-case-failed?answertab=active#tab-top) 
*/
bool current_test_passing()
{
 Â  using namespace boost::unit_test;
 Â  auto const id = framework::current_test_case().p_id;
 Â  auto const test_results = results_collector.results(id);
 Â  return test_results.passed();
}

std::string report_diagnostic(fs::path const& test_case_name, 
std::string const& input, std::string const& result)
{
 Â Â Â  ...
 Â Â Â  if(!x3_test::current_test_passing()) { Â Â Â  // only write in case of 
failed test
 Â Â Â Â Â Â Â  test_case_result_writer result_writer(test_case_name);
 Â Â Â Â Â Â Â  result_writer.write(result);
 Â Â Â  }
 Â Â Â  return ss.str();
}

} // x3_test

...

BOOST_AUTO_TEST_SUITE(....

BOOST_DATA_TEST_CASE( declaration,
 Â Â Â Â Â Â  dataset.input()
 Â Â Â  ^ dataset.expect()
 Â Â Â  ^ dataset.test_case_name(),
 Â Â Â  code, expect_AST, test_case_name)
{
 Â Â Â  using attribute_type = ast::declaration;
 Â Â Â  auto const parser = parser::declaration;

 Â Â Â  x3_test::testing_parser<attribute_type> parse;
 Â Â Â  auto [parse_ok, parsed_AST] = parse(code, parser);

 Â Â Â  BOOST_TEST(parse_ok);
 Â Â Â  BOOST_REQUIRE_MESSAGE(parse_ok,
 Â Â Â Â Â Â Â  x3_test::report_diagnostic(test_case_name, code, parsed_AST)
 Â Â Â  );

 Â Â Â  BOOST_TEST(parsed_AST == expect_AST, btt::per_element());
 Â Â Â  BOOST_REQUIRE_MESSAGE(x3_test::current_test_passing(),
 Â Â Â Â Â Â Â  x3_test::report_diagnostic(test_case_name, code, parsed_AST)
 Â Â Â  );
}

BOOST_AUTO_TEST_SUITE_END()

After some testing, the error count is twice the real (obviously here) 
but it's all above a work arround.

It seems, that BOOST_REQUIRE_MESSAGE evaluates always the message 
predicate (shown by using --log_level=all) nevertheless the test case 
successed or failed. If failed it is streamed to the console.

My first thoughs where that the message is called only in case of test 
failure which isn't true.

The problem is now, that my report_diagnostic function write the test 
output (parsed_AST) to a special dir/file for later evaluating etc. The 
intuitive way would be:

std::string report_diagnostic(fs::path const& test_case_name, 
std::string const& input, std::string const& result)
{
 Â Â Â  ...
 Â Â Â  test_case_result_writer result_writer(test_case_name);
 Â Â Â  result_writer.write(result);

 Â Â Â  return ss.str();
}

BOOST_REQUIRE_MESSAGE(parse_ok,
 Â Â Â Â Â Â Â  // call diagnostic only in failure case and write then
 Â Â Â Â Â Â Â  x3_test::report_diagnostic(test_case_name, code, parsed_AST)
 Â Â Â  );
BOOST_REQUIRE_MESSAGE((parsed_AST == expect_AST, btt::per_element()),
 Â Â Â Â Â Â Â  // call diagnostic only in failure case and write then
 Â Â Â Â Â Â Â  x3_test::report_diagnostic(test_case_name, code, parsed_AST)
 Â Â Â  );

Hence not depending on current_test_passing() any more.

How to get this?

Further, how can I get the captured std::cerr in case of '!parse_ok' 
inside report_diagnostic?

Thanks,

Olaf