Once you have everything prepared to write your Unit Tests it is worth to mention about mocking. There is new framework called "SimpleStubs" which enables you to create mocks based on the interfaces.
Simple case from GitHub documentation:
//Sample interface:
public interface IPhoneBook
{
long GetContactPhoneNumber(string firstName, string lastName);
long MyNumber { get; set; }
event EventHandler<long> PhoneNumberChanged;
}
//Mocked interface:
var stub = new StubIPhoneBook().GetContactPhoneNumber((firstName, lastName) => 6041234567);
You can read more about it here: https://github.com/Microsoft/SimpleStubs