The master test suite of type master_test_suite_t is the starting point for the test runner.

namespace boost { namespace unit_test {

class BOOST_TEST_DECL master_test_suite_t : public test_suite {
public:
    master_test_suite_t() : test_suite( "Master Test Suite" )
    , argc( 0 )
    , argv( 0 )
    {}

    // Data members
    int      argc;
    char**   argv;
};

} }

You can obtain a reference to the master test suite with the master_test_suite() function:

namespace boost { namespace unit_test { namespace framework {

BOOST_TEST_DECL master_test_suite_t& master_test_suite();

} } }