Hi, With the following test case: #include <boost/array.hpp> template<typename T,size_t N> std::ostream operator<<(const std::ostream & os, const boost::array<T,N> & arr) { os << "[ "; for(size_t i = 0 ; i < N-1; ++i) { os << arr[i] << ", "; } os << arr[N-1] << " ]"; return os; } BOOST_AUTO_UNIT_TEST ( test_boost_test_array ) { boost::array<double,3> arr1[] = { {{1,0,0}}, {{1,2,2}} }; boost::array<double,3> arr2[] = { {{1,0,0}}, {{1,2,2}} }; BOOST_REQUIRE_EQUAL_COLLECTIONS(arr1,arr1+2, arr2,arr2+2); } I'm getting odd compile errors at this line: res.message() << "\nMismatch in a position " << pos << ": " << *left_begin << " != " << *right_begin; gcc.compile.c++ bjam-build/gcc/release/unit_tests/data_utils.o external/boost/include/boost/test/utils/wrap_stringstream.hpp: In function âboost::basic_wrap_stringstream<CharT>& boost::operator<<(boost::basic_wrap_stringstream<CharT>&, const T&) [with CharT = char, T = boost::array<double, 3u>]â: external/boost/include/boost/test/test_tools.hpp:495: instantiated from âboost::test_tools::predicate_result boost::test_tools::tt_detail::equal_coll_impl(Left, Left, Right, Right) [with Left = boost::array<double, 3u>*, Right = boost::array<double, 3u>*]â unit_tests/data_utils.cpp:62: instantiated from here external/boost/include/boost/test/utils/wrap_stringstream.hpp:66: error: no match for âoperator<<â in â(+ targ)->boost::basic_wrap_stringstream<CharT>::stream [with CharT = char]() << tâ What am I missing here? Sorry for the long email! TIA, Sohail