_STRING
text_test_interpreter::failures(const test_result& result) const
{
    _STRING Result("Failures: ");
    _APPEND(Result, _yak_itoa(result.failures().size()));
    _APPEND(Result, "\n");
    _APPEND(Result, problem_vector_string(result.failures()));
    _APPEND(Result, "\n");
    return Result;
}