by MJ Facade is one of design patterns which are used most frequently. To explain what it is and how to use it, we can compare it to a black box. In black box test, tester is only allowed to create the input and get the output. He doesn’t know anything about processing inside of the system. You will meet similar situation in Facade – you don’t want to show out the whole functionality, you need to create some kind of interface which enables user to use the functonality, but he  cannot look into the syste...