Should each class have an interface?
From a purely object-oriented perspective, every class already has an interface. An interface is nothing more than the public-facing methods and data members of a class.
Can a class have interface?
Yes, you can define an interface inside a class and it is known as a nested interface. You can’t access a nested interface directly; you need to access (implement) the nested interface using the inner class or by using the name of the class holding this nested interface.
What is code to interface?
Coding to interfaces is a technique by which developers can expose certain methods of an object to other objects in the system. In other words, the developers would write code that did not interact directly with an object as such, but rather with the implementation of that object’s interface.
Should I use interface or class?
You should use an interface if you want a contract on some behavior or functionality. You should not use an interface if you need to write the same code for the interface methods. In this case, you should use an abstract class, define the method once, and reuse it as needed.
How can you unit test an interface that is supported by different classes?
In the simplest way, I could write three test class : ATest, BTest, CTest and test them separately. However, since they support the same interface, most test code would be the same, it’s hard to maintain. How can I use a simple and easy way to test a interface that is supported by different class?
Do you need an interface for a class?
No. Interfaces are good for classes with complex behaviour, and are especially handy if you want to be able to create a mock or fake implementation class of that interface for use in unit tests. But, some classes don’t have a lot of behaviour and can be treated more like values and usually consist of a set of data fields.
How to unit test an interface using NUnit?
If you want to run the same tests against different implementers of your interface using NUnit as an example:
Do you write unit tests or system tests?
If, like me, you start your programming career writing system tests, unit tests are probably something other people write. You probably have an idea about the unit tests written by your developers, you may even help review them, but you work solidly on testing completed systems.