Hi guys, Using the boost unit test framework, I'm trying to test a simple scenario: when a person's name is set, their 'updated' signal is triggered. Here's my person class: class person { public: person() : name_() {}; void name(const std::string & name) { name_ = name; updated(*this); }; boost::signal<void(const person & person)> updated; private: std::string name_; }; To test this, I've created a mock handler for the updated event. In it's destructor, it checks has been called (and also with the correct subject): struct mock_handler { mock_handler(const person & subject) : has_been_called_(false), subject_(subject) {}; // Handler. void operator()(const person & subject) { BOOST_TEST_MESSAGE("in mock_handler::operator()"); has_been_called_ = true; BOOST_CHECK_EQUAL(&subject == &subject_, true); }; // This handler must be called before it goes out of scope. ~mock_handler() { BOOST_TEST_MESSAGE("in mock_handler::~mock_handler()"); BOOST_CHECK_EQUAL(has_been_called_, true); }; private: bool has_been_called_; const person & subject_; }; And then writing my test case to use it: BOOST_AUTO_TEST_CASE(setting_name_triggers_update_signal) { BOOST_TEST_MESSAGE("entered test"); person subject; mock_handler handler(subject); subject.updated.connect(handler); subject.name("Richard"); BOOST_TEST_MESSAGE("exiting test"); } Unfortunately, when this code runs, it produces the following output: Running 1 test case... entered test in mock_handler::~mock_handler() test.cpp(46): error in "setting_name_triggers_update_signal": check has_been_called_ == true failed [0 != 1] in mock_handler::~mock_handler() test.cpp(46): error in "setting_name_triggers_update_signal": check has_been_called_ == true failed [0 != 1] in mock_handler::~mock_handler() test.cpp(46): error in "setting_name_triggers_update_signal": check has_been_called_ == true failed [0 != 1] in mock_handler::operator() exiting test in mock_handler::~mock_handler() test.cpp(46): error in "setting_name_triggers_update_signal": check has_been_called_ == true failed [0 != 1] in mock_handler::~mock_handler() *** 4 failures detected in test suite "tests" I'm not sure what's going on here, or why mock_handler's destructor is being called 4 extra times. Can anyone shed some light as to why this might be happening? Cheers, Rich