turtle/build/boost/doc/limitations.qbk

[section Limitations]

This section lists the library known limitations.

[section No support for unicode logging]

There is no support for unicode logging mainly because Boost.Test does not support it either.

[endsect]

[section Litteral 0 cannot be used as null pointer in constraints]

Given :

 class base
 {
 public:
     virtual void method( int i* ) = 0;
 };
 
 MOCK_BASE_CLASS( mock_base, base )
 {
     MOCK_METHOD( method, 1 )
 };

The following code does not compile :

 mock_base m;
 MOCK_EXPECT( m.method ).with( mock::equal( 0 ) ); // this fails
 MOCK_EXPECT( m.method ).with( 0 );                // this fails too !

This is due to the fact that the library uses templates pretty heavily, and the litteral 0 is considered as an int when instantiating a template function.

A workaround is :

 MOCK_EXPECT( m.method ).with( mock::equal< int* >( 0 ) ); // this compiles

However a somewhat better solution would be :

 MOCK_EXPECT( m.method ).with( mock::negate );

[endsect]

[section Template methods cannot be mocked]

Given the following client code :

 class concept
 {
 public:
     template< typename T >
     void method( T t )
     {}
 };
 
 template< typename T >
 class client
 {
 public:
     client( T t )             // T is supposed to model the previous concept
     {
         t.method( 42 );
         t.method( "string" );
     }
 };

Writing a mock object modeling 'concept' requires to list all the possible versions of 'method' :

 MOCK_CLASS( mock_concept )
 {
    MOCK_METHOD_EXT( method, 1, void( int ), method_int )
    MOCK_METHOD_EXT( method, 1, void( const char* ), method_string )
 };

While still somewhat possible, mocking a template method is indeed a bit cumbersome.

[endsect]

[section A private pure virtual method cannot be mocked using MOCK_METHOD]

The following code does not compile :

 class base
 {
 private:
     virtual void method() = 0;
 };
 
 MOCK_BASE_CLASS( mock_base, base )
 {
     MOCK_METHOD( method, 0 )       // this fails to compile because 'method' is not visible
 };

The workaround would be to use MOCK_METHOD_EXT :

 MOCK_BASE_CLASS( mock_base, base )
 {
     MOCK_METHOD_EXT( method, 0, void(), method )
 };

[endsect]

[section Commas are not allowed in templates in MOCK_BASE_CLASS]

The following code does not compile :

 template< typename T1, typename T2 >
 struct my_base_class
 {};
 
 MOCK_BASE_CLASS( my_mock, my_base_class< int, int > ) // this fails to compile because the pre-processor believes the macro to be called with 3 arguments
 {};

One workaround is :

 typedef my_base_class< int, int > my_base_type;
 
 MOCK_BASE_CLASS( my_mock, my_base_type )
 {};

Of course this is not always possible, as in :

 template< typename T1, typename T2 >
 MOCK_BASE_CLASS( my_mock, my_base_type< T1, T2 > )
 {};

Another workaround would make use of [@http://www.boost.org/libs/preprocessor Boost.Preprocessor] :

 template< typename T1, typename T2 >
 MOCK_BASE_CLASS( my_mock, my_base_type< T1 BOOST_PP_COMMA() T2 > )
 {};

Actually BOOST_PP_COMMA implementation is quite trivial, being only :

 #define BOOST_PP_COMMA() ,

Finally another workaround would be to not use the macro at all :

 template< typename T1, typename T2 >
 struct my_mock : my_base_type< T1, T2 >, mock::object
 {};

The extra features provided by MOCK_BASE_CLASS are not usable with template base classes anyway because there is no equivalent of MOCK_METHOD for them.

[endsect]

[section Warning C4505: '...' : unreferenced local function has been removed]

Example :

[teletype]

 warning C4505: 'base::[thunk]: __thiscall base::`vcall'{0,{flat}}' }'' : unreferenced local function has been removed

[c++]

This seems to be a random bug with some versions of the Microsoft Visual Studio compiler, see https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=324427

The only known workaround is to disable the warning with a pragma :

 #pragma warning( disable: 4505 )

[endsect]

[section Warning C4301: '...': overriding virtual function only differs from '...' by const/volatile qualifier]

Example :

[teletype]

 warning C4301: '`anonymous-namespace'::base::method': overriding virtual function only differs from '`anonymous-namespace'::base::method' by const/volatile qualifier

[c++]

The following code produces this warning with some versions of the Microsoft Visual Studio compiler :

 class base
 {
 public:
     virtual void method( const int ) = 0;
 };
 
 MOCK_BASE_CLASS( mock_base, base )
 {
     MOCK_METHOD( method, 1 )                                // this produces the warning
     MOCK_METHOD_EXT( method, 1, void( const int ), method ) // this produces the warning too !
 };

The problem is that the 'const' is actually not part of the function signature and therefore cannot be introspected.

The first workaround would be to remove the 'const' all together.

This is more sensible than it first sounds, after all the 'const' is useless in this situation, indeed :

 class derived : public base
 {
 public:
     virtual void method( const int );
 };
 
 void derived::method( int )           // this compiles, links and is valid C++
 {}

Otherwise another workaround would be to provide a proxy method :

 MOCK_BASE_CLASS( mock_base, base )
 {
     void method( const int i )
     {
         method_stub( i );
     }
     MOCK_METHOD_EXT( method_stub, 1, void( int ), method )
 };

[endsect]

[section warning C4267: 'argument' : conversion from 'size_t' to 'unsigned int', possible loss of data]

Compiling under Microsoft Visual Studio with the /Wp64 flag produces this warning at various locations in the library code.

This is actually a bug in the compiler, for more information see [@http://connect.microsoft.com/VisualStudio/feedback/details/253172/incorrect-warning-c4267 incorrect-warning-c4267].

[endsect]

[endsect]