boost/libs/iostreams/test/stream_state_test.cpp

// (C) Copyright Frank Birbacher 2007
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)

// See http://www.boost.org/libs/iostreams for documentation.

#include <boost/config.hpp>
#include <boost/iostreams/categories.hpp>  // tags.
#include <boost/iostreams/detail/ios.hpp>  // openmode, seekdir, int types.
#include <boost/iostreams/detail/error.hpp>
#include <boost/iostreams/positioning.hpp>
#include <boost/iostreams/stream.hpp>
#include <boost/test/test_tools.hpp>
#include <boost/test/unit_test.hpp>

using boost::iostreams::detail::bad_read;
using boost::iostreams::detail::bad_seek;
using boost::iostreams::detail::bad_write;
using boost::iostreams::seekable_device_tag;
using boost::iostreams::stream;
using boost::iostreams::stream_offset;
using boost::unit_test::test_suite;

/* 
 * This test unit uses a custom device to trigger errors. The device supports
 * input, output, and seek according to the SeekableDevice concept. And each
 * of the required functions throw a special detail::bad_xxx exception. This
 * should trigger the iostreams::stream to set the badbit status flag.
 * Additionally the exception can be propagated to the caller if the exception
 * mask of the stream allows exceptions.
 *
 * The stream offers four different functions: read, write, seekg, and seekp.
 * Each of them is tested with three different error reporting concepts:
 * test by reading status flags, test by propagated exception, and test by
 * calling std::ios_base::exceptions when badbit is already set.
 *
 * In each case all of the status checking functions of a stream are checked.
 *
 * MSVCPRT (Visual Studio 2017, at least) does not perform exception
 * handling in the seek methods (confirmed by inspecting sources).
 *
 * CYGWIN (with gcc-7.3.0) does not behave properly on the throw_delayed cases.
 */

//------------------Definition of error_device--------------------------------//

// Device whose member functions throw
struct error_device {
    typedef char                 char_type;
    typedef seekable_device_tag  category;
    error_device(char const*) {}
    std::streamsize read(char_type*, std::streamsize)
    {
        throw bad_read();
    }
    std::streamsize write(const char_type*, std::streamsize)
    {
        throw bad_write();
    }
    std::streampos seek(stream_offset, BOOST_IOS::seekdir)
    {
        throw bad_seek();
    }
};

typedef stream<error_device> test_stream;

//------------------Stream state tester---------------------------------------//

void check_stream_for_badbit(const std::iostream& str)
{
    BOOST_CHECK_MESSAGE(!str.good(), "stream still good");
    BOOST_CHECK_MESSAGE(!str.eof(), "eofbit set but not expected");
    BOOST_CHECK_MESSAGE(str.bad(), "stream did not set badbit");
    BOOST_CHECK_MESSAGE(str.fail(), "stream did not fail");
    BOOST_CHECK_MESSAGE(str.operator ! (),
            "stream does not report failure by operator !");
    BOOST_CHECK_MESSAGE(false == static_cast<bool>(str),
            "stream does not report failure by operator void* or bool");
}

//------------------Test case generators--------------------------------------//

template<void (*const function)(std::iostream&)>
struct wrap_nothrow {
    static void execute()
    {
        test_stream stream("foo");
        BOOST_CHECK_NO_THROW( function(stream) );
        check_stream_for_badbit(stream);
    }
};

template<void (*const function)(std::iostream&)>
struct wrap_throw {
    static void execute()
    {
        typedef std::ios_base ios;
        test_stream stream("foo");
        
        stream.exceptions(ios::failbit | ios::badbit);
        BOOST_CHECK_THROW( function(stream), std::exception );
        
        check_stream_for_badbit(stream);
    }
};

template<void (*const function)(std::iostream&)>
struct wrap_throw_delayed {
    static void execute()
    {
        typedef std::ios_base ios;
        test_stream stream("foo");
        
        function(stream);
        BOOST_CHECK_THROW(
                stream.exceptions(ios::failbit | ios::badbit),
                ios::failure
            );
        
        check_stream_for_badbit(stream);
    }
};

//------------------Stream operations that throw------------------------------//

void test_read(std::iostream& str)
{
    char data[10];
    str.read(data, 10);
}

void test_write(std::iostream& str)
{
    char data[10] = {0};
    str.write(data, 10);
        //force use of streambuf
    str.flush();
}

void test_seekg(std::iostream& str)
{
    str.seekg(10);
}

void test_seekp(std::iostream& str)
{
    str.seekp(10);
}

test_suite* init_unit_test_suite(int, char* []) 
{
    test_suite* test = BOOST_TEST_SUITE("stream state test");
    
    test->add(BOOST_TEST_CASE(&wrap_nothrow      <&test_read>::execute));
    test->add(BOOST_TEST_CASE(&wrap_throw        <&test_read>::execute));
#ifndef __CYGWIN__
    test->add(BOOST_TEST_CASE(&wrap_throw_delayed<&test_read>::execute));
#endif
    
    test->add(BOOST_TEST_CASE(&wrap_nothrow      <&test_write>::execute));
    test->add(BOOST_TEST_CASE(&wrap_throw        <&test_write>::execute));
#ifndef __CYGWIN__
    test->add(BOOST_TEST_CASE(&wrap_throw_delayed<&test_write>::execute));
#endif
    
#ifndef BOOST_MSVC
    test->add(BOOST_TEST_CASE(&wrap_nothrow      <&test_seekg>::execute));
    test->add(BOOST_TEST_CASE(&wrap_throw        <&test_seekg>::execute));
#ifndef __CYGWIN__
    test->add(BOOST_TEST_CASE(&wrap_throw_delayed<&test_seekg>::execute));
#endif
    
    test->add(BOOST_TEST_CASE(&wrap_nothrow      <&test_seekp>::execute));
    test->add(BOOST_TEST_CASE(&wrap_throw        <&test_seekp>::execute));
#ifndef __CYGWIN__
    test->add(BOOST_TEST_CASE(&wrap_throw_delayed<&test_seekp>::execute));
#endif
#endif // BOOST_MSVC

    return test;
}