如何对使用实体框架的存储库模式进行单元测试？

Question

我目前正在尝试对通过 Entity Framework 创建的存储库进行单元测试：

我希望在不实际发送/连接到实际数据库的情况下测试存储库，我希望不使用任何模拟框架。

目前我的测试是将数据发送到数据库，我想要测试添加/删除等方法而不将实际数据发送到数据库，因为它仅用于测试。

这里是存储库：

namespace AbstractFactory.Repository
{
    using System.Collections.Generic;
    using System.Data.Entity;
    using System.Linq;

    /// <summary>
    /// This class serves as the structure of the Author repository using a database
    /// </summary>
    public class DbAuthorRepository : IRepository<AuthorEntity>
    {

        private AbstractFactoryPatternEntities context;

        public DbAuthorRepository(AbstractFactoryPatternEntities context)
        {
            this.context = context;
        }

        /// <summary>
        /// Adds the specified author.
        /// </summary>
        /// <param name="author">The author.</param>
        public void Add(AuthorEntity author)
        {
            context.AuthorEntities.Add(author);
        }

        /// <summary>
        /// Removes the specified author.
        /// </summary>
        /// <param name="author">The author.</param>
        public void Remove(AuthorEntity author)
        {
            this.context.AuthorEntities.Remove(author);
        }

        /// <summary>
        /// Saves this instance.
        /// </summary>
        public void Save()
        {
            this.context.SaveChanges();
        }

        /// <summary>
        /// Gets all.
        /// </summary>
        /// <returns>returns a list of all the authors</returns>
        public IEnumerable<AuthorEntity> GetAll()
        {
            List<AuthorEntity> result = this.context.AuthorEntities.Include(a => a.Books).ToList();

            return result;
        }

        /// <summary>
        /// Gets the author by id.
        /// </summary>
        /// <param name="id">The id.</param>
        /// <returns>returns an entity</returns>
        public AuthorEntity GetById(int id)
        {
            AuthorEntity result = this.context.AuthorEntities.Single(a => a.AuthorId == id);

            return result;
        }
    }
}

这是当前单元测试的代码：

[TestMethod]
        public void Add_MethodIsCalled_EntityCountIsIncrementedByOne()
        {
            using (ShimsContext.Create())
            {
                ShimAbstractFactoryPatternEntities context = new ShimAbstractFactoryPatternEntities(new AbstractFactoryPatternEntities());
                DbAuthorRepository repository = new DbAuthorRepository(context);
                repository.Add(new AuthorEntity { FirstName = "Test", LastName = "testing=" });
                var actual = repository.GetAll().Count();
                repository.Save();
                var expected = repository.GetAll().Count();
                Assert.AreNotEqual(actual, expected);
            }

            //AbstractFactoryPatternEntities context = new AbstractFactoryPatternEntities();
            //DbAuthorRepository repository = new DbAuthorRepository(context);
            //var actual = repository.GetAll().Count();
            //repository.Add(new AuthorEntity { FirstName = "Testing", LastName = "MyTest" });
            //repository.Save();
            //var expected = repository.GetAll().Count();
            //Assert.AreNotEqual(actual, expected);
        }

        [TestMethod]
        public void Remove_MethodIsCalled_EntityCountRemainsTheSame()
        {
            AbstractFactoryPatternEntities context = new AbstractFactoryPatternEntities();
            DbAuthorRepository repository = new DbAuthorRepository(context);
            AuthorEntity newAuthor = new AuthorEntity { FirstName = "Testing", LastName = "MyTest" };
            repository.Add(newAuthor);
            repository.Save();
            var actual = repository.GetAll().Count();
            Console.WriteLine(actual);
            repository.Remove(newAuthor);
            var expected = repository.GetAll().Count();
            Console.WriteLine(expected);
            Assert.AreEqual(actual, expected);
        }

        [TestMethod]
        public void Get_MethodIsCalled_CorrectAuthorIsRetrieved()
        {
            AbstractFactoryPatternEntities context = new AbstractFactoryPatternEntities();
            DbAuthorRepository repository = new DbAuthorRepository(context);
            int target = 4;
            AuthorEntity author = repository.GetById(target);
            Assert.AreEqual(target, author.AuthorId);
        }

我想使用 shims/stub/fakes 来进行测试。

Answer 1

实体框架存储库是存储库接口的具体实现。因为它是具体的，所以你不能在没有数据库的情况下对其进行抽象和测试——这个具体实现的重点就是将数据写入数据库！

这意味着测试 EF 存储库应该旨在验证存储库是否写入实际数据库 - 在测试的动作阶段调用存储库方法，在断言阶段使用任何其他方式从数据库获取数据（ ado.net 也许？）检查存储库是否完成了它的工作。

另一个不相关的事情是，您可以拥有另一个使用内存数据存储的存储库实现，并将此类内存存储库注入其他服务允许您在不写入物理数据库的情况下测试这些服务。您甚至可以模拟注入到其他服务的存储库，只是为了执行一些行为测试，即测试您的服务是否正确使用您的存储库。

Answer 2

您可以使用内存数据库替换与数据库的连接，例如 Effort。然后您可以测试您的存储库逻辑。更多详情可以找到here