For document::view variables "a" and "b", a failure of the Catch test statement "REQUIRE(a == b)" results in the following output:

1: /Users/rassi/work/mongo-cxx-driver/src/bsoncxx/test/bson_builder.cpp:938: FAILED:
1:   REQUIRE( a == b )
1: with expansion:
1:   {?} == {?}

Instead of printing a question mark for "a" and "b", their JSON representations should be printed instead.

This may be as simple as providing a "operator<<(std::ostream&, document::view)" overload in the right place which streams the result of to_json().