turtle/build/boost/doc/patterns.qbk

[section Patterns]

This section highlights not-so-obvious features of the library gathered from real use cases.

[section Waiting for an asynchronous call]

Problem :

 namespace
 {
     class base_class
     {
     public:
         virtual void method() = 0;
     };
 
     class my_class
     {
     public:
         explicit my_class( base_class& );
 
         void flush(); // repetitively calling this method will in turn call base_class::method at some point
     };
 }

Solution :

 #include <turtle/mock.hpp>
 #include <boost/lambda/lambda.hpp>
 #include <boost/thread.hpp>
 
 namespace
 {
     template< typename F >
     void wait( bool& condition, F flush, int timeout = 100, int sleep = 100 )
     {
         while( !condition && timeout > 0 )
         {
             --timeout;
             boost::this_thread::sleep( boost::posix_time::milliseconds( sleep ) );
             flush();
         }
     }
     MOCK_BASE_CLASS( mock_base_class, base_class )
     {
         MOCK_METHOD( method, 0 )
     };
 }
 
 BOOST_AUTO_TEST_CASE( method_is_called )
 {
     mock_base_class mock;
     my_class c( mock );
     bool done = false;
     MOCK_EXPECT( mock.method ).once().calls( boost::lambda::var( done ) = true ); // when method is called it will set done to true
     wait( done, boost::bind( &my_class::flush, &c ) );                            // just wait on done flushing from time to time
 }

[endsect]

[section Retrieving an argument to use in a later constraint]

Problem :

 namespace
 {
     class base_class
     {
     public:
         virtual void method( int value ) = 0;
     };
 
     class my_class
     {
     public:
         explicit my_class( base_class& );
 
         void process(); // the processing will call 'method' two times with the same value, but we don't know what value beforehand
     };
 }

Solution :

 #include <turtle/mock.hpp>
 
 namespace
 {
     MOCK_BASE_CLASS( mock_base_class, base_class )
     {
         MOCK_METHOD( method, 1 )
     };
 }
 
 BOOST_AUTO_TEST_CASE( method_is_called_two_times_with_the_same_value )
 {
     mock_base_class mock;
     my_class c( mock );
     int value;
     MOCK_EXPECT( mock.method ).once().with( mock::retrieve( value ) ); // on first call retrieve the value, this expectation takes precedence because it can never fail
     MOCK_EXPECT( mock.method ).once().with( boost::cref( value ) );    // on second call compare the previously retrieved value with the newly received one
     c.process();
 }

[endsect]

[section Invoking a functor received as parameter]

 #include <turtle/mock.hpp>
 #include <boost/function.hpp>
 #include <boost/bind/apply.hpp>
 #include <boost/bind.hpp>
 
 namespace
 {
     MOCK_CLASS( mock_class )
     {
         MOCK_METHOD_EXT( method, 1, void( boost::function< void( int ) > ), method )
     };
 }
 
 BOOST_AUTO_TEST_CASE( how_to_invoke_a_functor_passed_as_parameter_of_a_mock_method )
 {
     mock_class mock;
     MOCK_EXPECT( mock.method ).calls( boost::bind( boost::apply< void >(), _1, 42 ) ); // whenever 'method' is called, invoke the functor with 42
     MOCK_FUNCTOR( f, void( int ) );                                                    // create a mock functor to verify this
     MOCK_EXPECT( f ).once().with( 42 );                                                // expect it to be called with 42
     mock.method( f );                                                                  // call 'method' with the mock functor
 }

[endsect]

[endsect]