Unit Of Work Starter Kit

Summary

The UnitOfWork package provides a lightweight starter kit for using the UOW, and Repository patterns with Entity Framework. It has been implemented in an easily testable way, so that you can mock data access to make testing easier.

A complimentary package to this is UnitOfWork.Test. This shows you how you can mock out the repositories for more control and isolation during your unit tests.

Data Access Unit Testing

You will want to do integration testing between your code and the DB. This is needed to ensure that your columns/entities are corrently mapped and that the DB constraints are not broken. To accomplish this simply add an app.config to your unit test project and add a connection string with the same name as your context. Point this to a localdb instance of SQL, and the DataInitialiser will create a DB for you.

Logic Unit Testing

With complex entities it can become a complicated and involved task to set up data structures in your DB for tests to work. In these cases it's easier to mock out the DB and hard code some entites for your tests to use. This can be done with a mocking framework (like NSubstitute) and and IoC container. For example:

var mock = Substitute.For<IUnitOfWork>();  
mock.Customers.GetByName("").ReturnsForAnyArgs(GetCustomers());  
DataContainer.RegisterInstance(mock);

IoC Container

Unity is used as the IoC container. You can replace this with your favourite IoC container by changing the implementation of DataContainer or UnitOfWork.Begin()

ORM

Entity Framework Code First is used as the ORM. This can be changed by re-implementing your repositories to use any other ORM or even stored procedures!

Automatic timestamping entities is implemented for anything that is created or modified. For this to work your entities just need to inherit from Entity.

Repository

The purpose of the repository is to wrap whatever data access technology you are using. The repository should also contain your LINQ queries so that these can be reused by different parts of your business logic.

You can use the generic repository to quickly get basic CRUD functionality working or you can extend this like the CustomerRepository does to add more functionality.

Unit Of Work

The purpose of the UOW is to provide transactions across operations on multiple repositories. That means that if you add/modifiy/delete entites across multiple repositories, either all the operations will succeed, or none of them will.

A UOW should be used in the following way:

using (var uow = UnitOfWork.Begin())
{
  // Put your code here...
}

Begin() is a factory method for creating a UOW. This allows us to swap out a real UOW for a mock UOW during our tests.

Project structure

The project contains two nuget packages UnitOfWork and UnitOfWork.Test. Each nuget package contains two projects. One for the actual package, and a target which can be used to test and consume the package.

NuGet Packages

The following packages can be installed to get this code via Nuget:

• UnitOfWork
• UnitOfWork.Test