模拟EF核心dbcontext和dbset

Question

我正在使用ASP.NET Core 2.2，EF Core和MOQ。当我运行测试时，出现此错误：

消息：System.NotSupportedException：在非虚拟（在VB中可重写）成员上的无效设置：x => x.Movies

我做错了什么？

public class MovieRepositoryTest
{
    private readonly MovieRepository _sut;

    public MovieRepositoryTest()
    {
        var moviesMock = CreateDbSetMock(GetFakeListOfMovies());
        var mockDbContext = new Mock<MovieDbContext>();
        mockDbContext.Setup(x => x.Movies).Returns(moviesMock.Object);
        _sut = new MovieRepository(mockDbContext.Object);
    }

    [Fact]
    public void GetAll_WhenCalled_ReturnsAllItems()
    {
        //Act
        var items = _sut.GetAll();

        //Assert
        Assert.Equal(3, items.Count());
    }

    private IEnumerable<Movie> GetFakeListOfMovies()
    {
        var movies = new List<Movie>
        {
            new Movie {Id = 1, Title = "Movie 1", YearOfRelease = 2018, Genre = "Action"},
            new Movie {Id = 2, Title = "Movie 2", YearOfRelease = 2018, Genre = "Action"},
            new Movie {Id = 3, Title = "Movie 3", YearOfRelease = 2019, Genre = "Action"}
        };

        return movies;
    }

    private static Mock<DbSet<T>> CreateDbSetMock<T>(IEnumerable<T> elements) where T : class
    {
        var elementsAsQueryable = elements.AsQueryable();
        var dbSetMock = new Mock<DbSet<T>>();

        dbSetMock.As<IQueryable<T>>().Setup(m => m.Provider).Returns(elementsAsQueryable.Provider);
        dbSetMock.As<IQueryable<T>>().Setup(m => m.Expression).Returns(elementsAsQueryable.Expression);
        dbSetMock.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(elementsAsQueryable.ElementType);
        dbSetMock.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(elementsAsQueryable.GetEnumerator());

        return dbSetMock;
    }
  }

这是我的数据库上下文，带有MoviedbSet：

public class MovieDbContext: DbContext
{
    public MovieDbContext(DbContextOptions<MovieDbContext> options) : base(options)
    {

    }

    public DbSet<Movie> Movies { get; set; }
}

并使用GetAll要测试的方法的存储库：

 public class MovieRepository: IMovieRepository
{
    private readonly MovieDbContext _moviesDbContext;
    public MovieRepository(MovieDbContext moviesDbContext)
    {
        _moviesDbContext = moviesDbContext;
    }

    public IEnumerable<Movie> GetAll()
    {
        return _moviesDbContext.Movies;
    }
}

Answer 1

使用Moq.EntityFrameworkCore包。

这很简单：

using Moq.EntityFrameworkCore;

var myDbContextMock = new Mock<MyDbContext>();
var entities = new List<Entity>() { new Entity(), new Entity() };
myDbContextMock.Setup(x => x.Entities).ReturnsDbSet(entities);

Answer 2

我看你正在使用EF核心DbContext在你的MovieRepository。因此，代替使用模拟，使用EF Core InMemory数据库将是您的理想选择。这也将降低复杂度。

编写GetAllTest()方法如下：

[Fact]
public void GetAllTest()
{
        var options = new DbContextOptionsBuilder<MovieDbContext>()
            .UseInMemoryDatabase(databaseName: "MovieListDatabase")
            .Options;

        // Insert seed data into the database using one instance of the context
        using (var context = new MovieDbContext(options))
        {
            context.Movies.Add(new Movie {Id = 1, Title = "Movie 1", YearOfRelease = 2018, Genre = "Action"});
            context.Movies.Add(new Movie {Id = 2, Title = "Movie 2", YearOfRelease = 2018, Genre = "Action"});
            context.Movies.Add(nnew Movie {Id = 3, Title = "Movie 3", YearOfRelease = 2019, Genre = "Action"});
            context.SaveChanges();
        }

        // Use a clean instance of the context to run the test
        using (var context = new MovieDbContext(options))
        {
            MovieRepository movieRepository = new MovieRepository(context);
            List<Movies> movies == movieRepository.GetAll()

            Assert.Equal(3, movies.Count);
        }
}

注意：不要忘记Microsoft.EntityFrameworkCore.InMemory按以下方式安装nuget软件包：

安装包Microsoft.EntityFrameworkCore.InMemory

有关更多详细信息：使用InMemory测试

Answer 3

为了节省您的时间，请尝试使用我的 Moq/NSubstitute 扩展 MockQueryable：https : //github.com/romantitov/MockQueryable 支持所有同步/异步操作

//1 - create a List<T> with test items
var users = new List<UserEntity>()
{
 new UserEntity,
 ...
};

//2 - build mock by extension
var mock = users.AsQueryable().BuildMock();

//3 - setup the mock as Queryable for Moq
_userRepository.Setup(x => x.GetQueryable()).Returns(mock.Object);

//3 - setup the mock as Queryable for NSubstitute
_userRepository.GetQueryable().Returns(mock);

还支持 DbSet

//2 - build mock by extension
var mock = users.AsQueryable().BuildMockDbSet();

//3 - setup DbSet for Moq
var userRepository = new TestDbSetRepository(mock.Object);

//3 - setup DbSet for NSubstitute
var userRepository = new TestDbSetRepository(mock);

笔记：

• 从 1.0.4 版本开始支持 AutoMapper
• 从 1.1.0 版本开始支持 DbQuery
• 从 3.0.0 版本开始支持 EF Core 3.0