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，想将它用作数据的后备存储 - 但不接触实时数据库.

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，用于在整个应用程序中访问数据.
• Repository 表示 DbSet 的直接挂钩，由 DbContext 提供.
• 一个 DbContext 包含所有 DbSet.

这是我目前的测试:

        // 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());

我的测试似乎成功了，因为它可以验证用户是否已添加到模拟 DbSet - 但我需要做的实际上是取回该数据并对其执行进一步的断言(这只是一个临时测试).

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，测试框架正在我的头上.另外，如果它们更易于使用，我可以选择迁移到其他测试框架.

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，并使用后备集合模拟枚举数据库集

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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