AdoService.h

#include "IDbService.h"


class AdoService : public IDbService {

public:
	static AdoService& instance() override;
	QueryResult runQuery(string query) override;

};

DataModel.h

#include "AdoService.h"


class DataModel : public Persistable {

public:
	DataModel(DbService& dbService = AdoService::instance());
	
private:
	PersistenceReport readData() override;

};

IDbService.h

class IDbService {

public:
	static IDbService& instance() = 0;
	QueryResult runQuery(string query) = 0;

};

main.cpp

#include "DataModel.h"
#include "MockDbService.h"


int main() {
	DataModel model;

	DataModel testModel(MockDbService::instance());

	return 0;
}