struct mock_handler
{
mock_handler() :
has_been_called_(false)
{};

// The signal handler function.
void operator()(const person & person)
{
has_been_called_ = true;
received_person_ = person;
};

bool has_been_called()
{
return has_been_called_;
}

bool person_received()
{
return actual_person;
}

// This handler must be called before it goes out of scope.
~mock_handler()
{
};

private:
bool has_been_called_;
person& received_person_;
};

And then have:

// Test that setting a new name triggers the person.updated signal.
BOOST_AUTO_TEST_CASE(setting_name_triggers_update_signal)
{
person subject;
mock_handler handler(subject);

subject.updated.connect(boost::ref(handler));

// Change the person’s name, triggering the updated signal.
subject.name(“Richard”);

BOOST_CHECK_EQUAL(handler.has_been_called(), true);
BOOST_CHECK_EQUAL(handler.person_received(), subject);
}

This makes it more explicit as to what the handler is expecting to get, and may be easier to read/maintain.