The unit_test_log_t class encapsulates the unit test log. You obtain a reference to the single global unit test log instance with the unit_test_log member.

namespace boost { namespace unit_test { namespace log {

class BOOST_TEST_DECL unit_test_log_t : public test_observer, public singleton<unit_test_log_t> {
public:
    // test_observer interface implementation
    void                test_start( counter_t test_cases_amount );
    void                test_finish();
    void                test_aborted();

    void                test_unit_start( test_unit const& );
    void                test_unit_finish( test_unit const&, unsigned long elapsed );
    void                test_unit_skipped( test_unit const& );
    void                test_unit_aborted( test_unit const& );

    void                assertion_result( bool passed );
    void                exception_caught( execution_exception const& );

    virtual int         priority() { return 1; }

    // log configuration methods
    void                set_stream( std::ostream& );
    void                set_threshold_level( log_level );
    void                set_format( output_format );
    void                set_formatter( unit_test_log_formatter* );

    // test progress logging
    void                set_checkpoint( const_string file, std::size_t line_num, const_string msg = const_string() );

    // entry logging
    unit_test_log_t&    operator<<( log::begin const& );        // begin entry 
    unit_test_log_t&    operator<<( log::end const& );          // end entry
    unit_test_log_t&    operator<<( log_level );                // set entry level
    unit_test_log_t&    operator<<( const_string );             // log entry value
    unit_test_log_t&    operator<<( lazy_ostream const& );      // log entry value

    ut_detail::entry_value_collector operator()( log_level );   // initiate entry collection
};

namespace {
    unit_test_log_t& unit_test_log;
}

} } }