We have a class that has methods which implements threads:
class ThreadPool
{
//Thread creation and invocation
int Create();
};
Another class that embeds a ThreadPool in it
class Service
{
public:
ThreadPool mThreadPool;
int start();
}
int Service::start()
{
mThreadPoll.Create();
.......
}
Cause of the above design pattern I am unable to mock my Service class.
I am trying to write an interface class to ThreadPool and use it in Service class:
class InterfaceThreadPool
{
virtual int Create () = 0;
};
class ThreadPool : public InterfaceThreadPool
{
int Create () override;
};
My idea is to create an interface class ThreadPoolImpl which I can use it in my Service Class:
class Service : public ThreadPoolImpl
{
public:
int start();
}
int Service::start()
{
Create(); // as inherited from ThreadPoolImpl
.......
}
The benefit is that now I can mock my Service class. But I am unable defined ThreadPoolImpl class
class ThreadPoolImpl : public InterfaceThreadPool
{
int Create () override;
}
int ThreadPoolImpl::Create()
{
//how can I call ThreadPool Create
}
I actually disagree with @Jarod42 comments. If you would like to test and mock both your ThreadPool class and Service class, the comfortable way is to design it like that:
class InterfaceThreadPool
{
public:
virtual ~InterfaceThreadPool() = default;
virtual int Create () = 0;
};
class ThreadPool : public InterfaceThreadPool
{
public:
~ThreadPool() override;
int Create () override;
};
class IService
{
public:
virtual ~IService() = default;
virtual int start() = 0;
};
class Service: public IService
{
public:
/*
* InterfaceThreadPool might be passed by raw ptr, reference, smart ptr, whataver you like the most
*/
Service(InterfaceThreadPool* mThreadPool);
~Service() override;
int start() override { return mThreadPool_->Create(); }
private:
InterfaceThreadPool* mThreadPool_;
};
Then in your production code you use the appropriate implementation of Service along with ThreadPool. In your tests you can use:
MockThreadPool (derived from InterfaceThreadPool) to test ServiceMockThreadPool + MockService (derived from IService) to test some other things that need those two classesMockService + ThreadPool implementation invoked when start function is called (it's not very common, but maybe you can find it useful)Collected from the Internet
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