Hi all, I've been using Boost.Test lately and in general it's working well (thanks Gennadiy!). However, I'm having trouble with BOOST_CHECK_EQUAL_COLLECTIONS when my collections are of non-primitive types. For example, if I try: vector<wstring> test1, test2; BOOST_CHECK_EQUAL_COLLECTIONS(test1.begin(), test1.end(), test2.begin(), test2.end()); I get a compiler error along the lines of "h:\libraries\boost\boost\test\utils\wrap_stringstream.hpp(66) : error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const std::basic_string<_Elem,_Traits,_Ax>' (or there is no acceptable conversion)" (with _Elem being wchar_t in this case, and _Traits and _Ax having the usual defaults). Looking at the source I see that BOOST_CHECK_EQUAL_COLLECTIONS is using equal_coll_impl, which is creating a predicate_result and using the stream insertion operator on the wrap_stripstream returned by its message() method. wrap_stringstream has an unspecialized template which delegates to the << operator of the backing ostringstream/ostrstream: template inline basic_wrap_stringstream<CharT>& operator<<( basic_wrap_stringstream<CharT>& targ, T const& t ) { targ.stream() << t; return targ; } Since that backing ostringstream descends from ostream, I would have thought that all I needed to do was to ensure that there is a operator << (ostream&, wstring const&) defined, like this: ostream& operator << (ostream& ostr, wstring const& str) { ostr << "I'd put a wstring-to-string function here instead of this constant"; return ostr; } Hower this doesn't work - although I can now compile: ostringstream oss; oss << wstring(L"test"); successfully, if I try: boost::wrap_stringstream wss; wss << wstring(L"test"); or: boost::test_tools::predicate_result res(true); res.message() << wstring(L"test"); I get the same error as above. Interestingly, if I change that << operator implementation so that it takes and returns a wrap_stringstream, instead of an ostream: boost::wrap_stringstream& operator << (boost::wrap_stringstream& ostr, const wstring& str) { ostr << "I'd put a wstring-to-string function here instead of this constant"; return ostr; } then I can compile 'wss << wstring(L"test")' and ' res.message() << wstring(L"test")' OK. This is weird because it suggests to me that that unspecialized wrap_stringstream template that delegates to the ostringstream's << isn't working properly. But weirder is that even having done that, using BOOST_CHECK_EQUAL_COLLECTIONS still produces the same compilation error, even though it's making the same operator call - I can't see why. Am I missing something here? I also tried specializing print_log_value: namespace boost { namespace test_tools { namespace tt_detail { template<> struct print_log_valuestd::wstring { void operator()(std::ostream& ostr, const std::wstring& str) { ostr << "I'd put a wstring-to-string function here instead of this constant"; } }; }}} But that didn't help either - same error. I'm primarily using Visual Studio 2005, but I have exactly the same problems under gcc 3.3.5 too. Any suggestions? Cheers, Will -- Will Bryant http://carcino.gen.nz/ will@core-dev.co.nz +64 21 655 443