如何使用Entity Framework和Moq进行单元测试? [英] How do I go about unit testing with Entity Framework and Moq?

问题描述

我是Moq的新手，并且希望将其用作数据的后备存储-但又不影响实时数据库.

I'm new to Moq, and wanting to use it like a backing store for data - but without touching the live database.

我的设置如下:

• UnitOfWork包含所有存储库，并用于整个应用程序中的数据访问.
• 存储库表示直接连接到DbContext的DbSet中.
• DbContext包含所有DbSet.

到目前为止，这是我的测试:

Here is my test so far:

        // ARRANGE
        var user = new User()
        {
            FirstName = "Some",
            LastName = "Guy",
            EmailAddress = "[e-mail]",
        };

        var mockSet = new MockDbSet<User>();
        var mockContext = new Mock<WebAPIDbContext>();

        mockContext.Setup(c => c.Set<User>()).Returns(mockSet.Object);

        // ACT
        using (var uow = UnitOfWork.Create(mockContext.Object))
        {
            uow.UserRepository.Add(user);
            uow.SaveChanges();
        }

        // ASSERT
        mockSet.Verify(u => u.Add(It.IsAny<User>()), Times.Once());

我的测试似乎是成功的，因为它可以验证是否已将用户添加到模拟DbSet中-但我要做的实际上是将数据取回并对其执行进一步的声明(这只是临时的)测试).

My test seems to be successful, as it can verify that a user was added to the mock DbSet - but what I need to do is actually get that data back and perform further assertions on it (this is just an ad-hoc test).

请告知，测试框架正在发挥我的作用.此外，如果它们更易于使用，我可以选择使用其他测试框架.

Please advise, testing frameworks are doing my head in. Also, I have the option to move to other testing frameworks if they are easier to use.

谢谢.

更新:这是我的工作代码.

单元测试

        // ARRANGE
        var user = new User()
        {
            FirstName = "Some",
            LastName = "Guy",
            EmailAddress = "[e-mail]",
        };

        var mockSet = new MockDbSet<User>();
        var mockContext = new Mock<WebAPIDbContext>();

        mockContext.Setup(c => c.Set<User>()).Returns(mockSet.Object);

        // ACT
        using (var uow = UnitOfWork.Create(mockContext.Object))
        {
            uow.UserRepository.Add(user);
            uow.SaveChanges();
        }

        // ASSERT
        mockSet.Verify(u => u.Add(It.IsAny<User>()), Times.Once());

        // TODO: Further assertations can now take place by accessing mockSet.BackingStore.
    }

MockDbSet

class MockDbSet<TEntity> : Mock<DbSet<TEntity>> where TEntity : class
{
    public ICollection<TEntity> BackingStore { get; set; }

    public MockDbSet()
    {
        var queryable = (this.BackingStore ?? (this.BackingStore = new List<TEntity>())).AsQueryable();

        this.As<IQueryable<TEntity>>().Setup(e => e.Provider).Returns(queryable.Provider);
        this.As<IQueryable<TEntity>>().Setup(e => e.Expression).Returns(queryable.Expression);
        this.As<IQueryable<TEntity>>().Setup(e => e.ElementType).Returns(queryable.ElementType);
        this.As<IQueryable<TEntity>>().Setup(e => e.GetEnumerator()).Returns(() => queryable.GetEnumerator());

        // Mock the insertion of entities
        this.Setup(e => e.Add(It.IsAny<TEntity>())).Returns((TEntity entity) =>
        {
            this.BackingStore.Add(entity);

            return entity;
        });

        // TODO: Other DbSet members can be mocked, such as Remove().
    }
}

推荐答案

您只需要创建一个集合作为后备存储并模拟使用该后备集合设置的枚举数据库

You just need to create a collection to act as the backing store and mock the enumeration db set with the backing collection

public class MockDbSet<TEntity> : Mock<DbSet<TEntity>> where TEntity : class {
    public MockDbSet(List<TEntity> dataSource = null) {
        var data = (dataSource ?? new List<TEntity>());
        var queryable = data.AsQueryable();

        this.As<IQueryable<TEntity>>().Setup(e => e.Provider).Returns(queryable.Provider);
        this.As<IQueryable<TEntity>>().Setup(e => e.Expression).Returns(queryable.Expression);
        this.As<IQueryable<TEntity>>().Setup(e => e.ElementType).Returns(queryable.ElementType);
        this.As<IQueryable<TEntity>>().Setup(e => e.GetEnumerator()).Returns(() => queryable.GetEnumerator());
        //Mocking the insertion of entities
        this.Setup(_ => _.Add(It.IsAny<TEntity>())).Returns((TEntity arg) => {
            data.Add(arg);
            return arg;
        });

        //...the same can be done for other members like Remove
    }
}

所以现在您可以使用列表来保存数据

So now you can use a list to hold the data

// ARRANGE
var dataSource = new List<User>(); //<-- this will hold data
var user = new User()
{
    FirstName = "Some",
    LastName = "Guy",
    EmailAddress = "[e-mail]",
};

var mockSet = new MockDbSet<User>(dataSource);
var mockContext = new Mock<WebAPIDbContext>();

mockContext.Setup(c => c.Set<User>()).Returns(mockSet.Object);

// ACT
using (var uow = UnitOfWork.Create(mockContext.Object))
{
    uow.UserRepository.Add(user);
    uow.SaveChanges();


    // ASSERT
    mockSet.Verify(u => u.Add(It.IsAny<User>()), Times.Once());
    Assert.IsTrue(dataSource.Contains(user)); //<-- shows mock actually added item
    Assert.IsTrue(uow.UserRepository.Any(u => u == user)); //<-- show you can actually query mock DbSet
}

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