存储库模式和内存中的单元测试

Question

我已经看到了Repository Pattern的一些实现,非常简单和直观,在stackoverflow中链接形成其他答案

http://www.codeproject.com/Tips/309753/Repository-Pattern-with-Entity-Framework-4-1-and-C http://www.remondo.net/repository-pattern-example-csharp/

public interface IRepository<T>
{
    void Insert(T entity);
    void Delete(T entity);
    IQueryable<T> SearchFor(Expression<Func<T, bool>> predicate);
    IQueryable<T> GetAll();
    T GetById(int id);
}

public class Repository<T> : IRepository<T> where T : class, IEntity
{
    protected Table<T> DataTable;

    public Repository(DataContext dataContext)
    {
        DataTable = dataContext.GetTable<T>();
    }
...

在进行单元测试时,如何将其设置为在内存中工作？有没有办法从内存中的任何东西构建DataContext或Linq表？我的想法是创建一个集合(List,Dictionary ...)并在单元测试时将其存根.

谢谢!

编辑:我需要这样的东西:

• 我有一本班级书
• 我有一个班级图书馆

• 在Library构造函数中,我初始化了存储库:

  var bookRepository = new Repository<Book>(dataContext)

• 这些Library方法使用存储库,就像这样

  public Book GetByID(int bookID)
  { 
      return bookRepository.GetByID(bookID)
  }
  

在测试时,我想提供一个内存上下文.在生产中,我将提供真实的数据库上下文.

Answer 1

我建议使用像Moq或RhinoMocks这样的模拟库.可以在这里找到使用Moq的精彩教程.

在您决定使用哪一个之前,以下内容可能会有所帮助:

• http://graemef.com/blog/2011/02/10/A-quick-comparison-of-some-.NET-mocking-frameworks/

• http://jimmykeen.net/articles/09-jul-2012/mocking-frameworks-comparison-part-1-introduction

附加信息:单元测试框架的比较可以在这里找到.

根据OP的要求更新

创建内存数据库

var bookInMemoryDatabase = new List<Book>
{
    new Book() {Id = 1, Name = "Book1"},
    new Book() {Id = 2, Name = "Book2"},
    new Book() {Id = 3, Name = "Book3"}
};

模拟你的存储库(我使用Moq作为以下示例)

var repository = new Mock<IRepository<Book>>();

设置您的存储库

// When I call GetById method defined in my IRepository contract, the moq will try to find
// matching element in my memory database and return it.

repository.Setup(x => x.GetById(It.IsAny<int>()))
          .Returns((int i) => bookInMemoryDatabase.Single(bo => bo.Id == i));

通过在构造函数参数中传递模拟对象来创建库对象

var library = new Library(repository.Object);

最后一些测试:

// First scenario look up for some book that really exists 
var bookThatExists = library.GetByID(3);
Assert.IsNotNull(bookThatExists);
Assert.AreEqual(bookThatExists.Id, 3);
Assert.AreEqual(bookThatExists.Name, "Book3");

// Second scenario look for some book that does not exist 
//(I don't have any book in my memory database with Id = 5 

Assert.That(() => library.GetByID(5),
                   Throws.Exception
                         .TypeOf<InvalidOperationException>());

// Add more test case depending on your business context
.....