EntityFrameworkCore中的IDbAsyncQueryProvider

问题描述

我正在使用XUNIT在点网核心应用程序中进行测试.

I'm using XUNIT to test in a dot net core application.

我需要测试一个在数据上下文中内部对DbSet进行异步查询的服务.

I need to test a service that is internally making an async query on a DbSet in my datacontext.

我在这里看到，可以异步嘲笑DbSet

I've seen here that mocking that DbSet asynchronously is possible.

我遇到的问题是IDbAsyncQueryProvider在我正在使用的EntityframeworkCore中似乎不可用.

The problem I'm having is that the IDbAsyncQueryProvider does not seem to be available in EntityframeworkCore, which I'm using.

我在这里不正确吗?其他人有没有这个工作?

Am I incorrect here? Has anyone else got this working?

(很长的一天，希望我只是缺少一些简单的东西)

(Been a long day, hopefully I'm just missing something simple)

编辑

在GitHub上询问后，我得到了指向此类的信息: https://github.com/aspnet/EntityFramework/blob/dev/src/Microsoft.EntityFrameworkCore/Query/Internal/IAsyncQueryProvider.cs

After asking on GitHub, I got point to this class:https://github.com/aspnet/EntityFramework/blob/dev/src/Microsoft.EntityFrameworkCore/Query/Internal/IAsyncQueryProvider.cs

这是到目前为止我尝试实现的目的:

This is what I've gotten to so far in trying to implement this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore.Query.Internal;

namespace EFCoreTestQueryProvider
{
    internal class TestAsyncQueryProvider<TEntity>: IAsyncQueryProvider
    {
        private readonly IQueryProvider _inner;

        internal TestAsyncQueryProvider(IQueryProvider inner)
        {
            _inner = inner;
        }

        IQueryable CreateQuery(Expression expression)
        {
            return new TestDbAsyncEnumerable<TEntity>(expression);
        }

        IQueryable<TElement> CreateQuery<TElement>(Expression expression)
        {
             return new TestDbAsyncEnumerable<TElement>(expression);
        }

        object Execute(Expression expression)
        {
            return _inner.Execute(expression);
        }

        TResult Execute<TResult>(Expression expression)
        {
            return _inner.Execute<TResult>(expression);
        }

        IAsyncEnumerable<TResult> ExecuteAsync<TResult>(Expression expression)
        {
            return Task.FromResult(Execute<TResult>(expression)).ToAsyncEnumerable();
        }

        Task<TResult> IAsyncQueryProvider.ExecuteAsync<TResult>(Expression expression, CancellationToken cancellationToken)
        {
            return Task.FromResult(Execute<TResult>(expression));
        }
    }

    internal class TestDbAsyncEnumerable<T> : EnumerableQuery<T>, System.Collections.Generic.IAsyncEnumerable<T>, IQueryable<T>
    {
        public TestDbAsyncEnumerable(IEnumerable<T> enumerable)
            : base(enumerable)
        { }

        public TestDbAsyncEnumerable(Expression expression)
            : base(expression)
        { }

        public IAsyncEnumerator<T> GetAsyncEnumerator()
        {
            return new TestDbAsyncEnumerable<T>(this.AsEnumerable()).ToAsyncEnumerable();
        }

        IDbAsyncEnumerator IDbAsyncEnumerable.GetAsyncEnumerator()
        {
            return GetAsyncEnumerator();
        }

        IAsyncEnumerator<T> IAsyncEnumerable<T>.GetEnumerator()
        {
            throw new NotImplementedException();
        }

        IQueryProvider IQueryable.Provider
        {
            get { return new TestAsyncQueryProvider<T>(this); }
        }
    }
}

我现在试图实现这一点，并遇到了更多的问题，特别是围绕这两种方法:

I've now tried to implement this and have run into some more issues, specifically around these two methods:

public IAsyncEnumerator<T> GetAsyncEnumerator()
{
    return new TestDbAsyncEnumerable<T>(this.AsEnumerable()).ToAsyncEnumerable();
}

IDbAsyncEnumerator IDbAsyncEnumerable.GetAsyncEnumerator()
{
    return GetAsyncEnumerator();
}

我希望有人可以指出我在做错事情的正确方向.

I'm hoping that somebody could point me in the right direction as to what I'm doing wrong.

推荐答案

我终于可以使用它了.他们将EntityFrameworkCore中的接口从IDbAsyncEnumerable更改为IAsyncEnumerable，因此以下代码对我有用:

I finally got this to work. They slightly changed the interfaces in EntityFrameworkCore from IDbAsyncEnumerable to IAsyncEnumerable so the following code worked for me:

public class AsyncEnumerable<T> : EnumerableQuery<T>, IAsyncEnumerable<T>, IQueryable<T>
{
    public AsyncEnumerable(Expression expression)
        : base(expression) { }

    public IAsyncEnumerator<T> GetEnumerator() =>
        new AsyncEnumerator<T>(this.AsEnumerable().GetEnumerator());
}

public class AsyncEnumerator<T> : IAsyncEnumerator<T>
{
    private readonly IEnumerator<T> enumerator;

    public AsyncEnumerator(IEnumerator<T> enumerator) =>
        this.enumerator = enumerator ?? throw new ArgumentNullException();

    public T Current => enumerator.Current;

    public void Dispose() { }

    public Task<bool> MoveNext(CancellationToken cancellationToken) =>
        Task.FromResult(enumerator.MoveNext());
}

[Fact]
public async Task TestEFCore()
{
    var data =
        new List<Entity>()
        {
            new Entity(),
            new Entity(),
            new Entity()
        }.AsQueryable();

    var mockDbSet = new Mock<DbSet<Entity>>();

    mockDbSet.As<IAsyncEnumerable<Entity>>()
        .Setup(d => d.GetEnumerator())
        .Returns(new AsyncEnumerator<Entity>(data.GetEnumerator()));

    mockDbSet.As<IQueryable<Entity>>().Setup(m => m.Provider).Returns(data.Provider);
    mockDbSet.As<IQueryable<Entity>>().Setup(m => m.Expression).Returns(data.Expression);
    mockDbSet.As<IQueryable<Entity>>().Setup(m => m.ElementType).Returns(data.ElementType);
    mockDbSet.As<IQueryable<Entity>>().Setup(m => m.GetEnumerator()).Returns(data.GetEnumerator());

    var mockCtx = new Mock<SomeDbContext>();
    mockCtx.SetupGet(c => c.Entities).Returns(mockDbSet.Object);

    var entities = await mockCtx.Object.Entities.ToListAsync();

    Assert.NotNull(entities);
    Assert.Equal(3, entities.Count());
}

您也许可以清理AsyncEnumerable和AsyncEnumerator的那些测试实现.我没有尝试，只是让它起作用.

You might be able to clean up those test implementations of the AsyncEnumerable and AsyncEnumerator even more. I didn't try, I just got it to work.

请记住，您需要将DbContext上的DbSet标记为virtual，否则您将需要在DbContext上实现一些接口包装，以使其正常工作.

Remember your DbSet on your DbContext needs to be marked as virtual or else you will need to implement some interface wrapper over the DbContext to make this work properly.

这篇关于EntityFrameworkCore中的IDbAsyncQueryProvider的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！