.Net Core 单元测试错误 - 源 IQueryable 未实现 IAsyncEnumerable<...>

Question

我有一行代码在单元测试中失败，但在开发和生产中运行良好。

var result = await _mapper.ProjectTo<GetApplicationsResponse.Application>(pipelineContext.Query).ToListAsync(cancellationToken);

pipelineContext.Query 是 IQueryable.

的类型

我要进行的测试如下

[Fact]
public async Task Handle_Success_Returns_GetApplicationsResponse()
{
    //Arrange
    var sut = CreateSut();

    _pipelineSteps
        .Setup(steps => steps.GetEnumerator())
        .Returns(() => new List<IPipelineStep<GetApplicationsContext>>
        {
            Mock.Of<IPipelineStep<GetApplicationsContext>>()
        }.GetEnumerator());

    _mapper.Setup(x => x.ConfigurationProvider)
        .Returns(
            () => new MapperConfiguration(
                cfg =>
                {
                    cfg.CreateMap<Entities.ApplicationsAggregate.Application, GetApplicationsResponse.Application>();
                    cfg.CreateMap<Entities.ApplicationsAggregate.SiteLocation, GetApplicationsResponse.SiteLocation>();
                    cfg.CreateMap<Entities.ApplicationsAggregate.SiteAddress, GetApplicationsResponse.SiteAddress>();
                }));

    //Act
    var result = await sut.Handle(new GetApplicationsRequest(), default);
    
    //Assert
    result.Should().BeOfType<GetApplicationsResponse>();
    _pipelineSteps.Verify(steps => steps.GetEnumerator(), Times.Once);
}

我在这方面的局限性是我无法更改 _projectTo<...>，因为这是新方法\工作标准。

所以，如果能帮助我解决这个错误，我将不胜感激

System.InvalidOperationException : The source IQueryable doesn't implement IAsyncEnumerable<TQ.Applications.Application.Queries.GetApplications.GetApplicationsResponse+Application>. Only sources that implement IAsyncEnumerable can be used for Entity Framework asynchronous operations.

---- 编辑 ---

之前忘记提到测试使用的是内存数据库

Answer 1

问题是 ToListAsync 想要一个实现 IAsyncEnumerable 的序列，但 ProjectTo 没有给它。

您正在使用 EntityFrameworkCore in-memory 提供程序，我假设您将其注入到 SUT 中并在失败时引用它。这是主要问题，因为 in-memory 提供程序不提供实现 IAsyncEnumerable 的序列。 ProjectTo 最终向 ToListAsync 提供了一个 IQueryable，这是行不通的。

至于如何解决，有两种方法。

lazy/right 方法：使用更好的 DbContext。

以下 LINQPad 示例使用 EntityFrameworkCore.Testing.Moq 创建可注入的 DbContext 以生成 IAsyncEnumerable 序列：

void Main()
{
    var fixture = new Fixture();

    var dataEntites = fixture.CreateMany<DataEntity>();
    var expectedResult = dataEntites.Select(x => new BusinessEntity() { id = x.Id, code = x.Code });

    var mapper = new Mapper(new MapperConfiguration(x => x.AddProfile(new MappingProfile())));
    var pipelineContext = Create.MockedDbContextFor<PipelineContext>();
    pipelineContext.Entities.AddRangeToReadOnlySource(dataEntites);

    var sut = new SUT(mapper, pipelineContext);

    var actualResult = sut.Handle().Result;

    var compareLogic = new CompareLogic();
    compareLogic.Config.IgnoreObjectTypes = true;
    compareLogic.Config.IgnoreCollectionOrder = true;
    var comparisonResult = compareLogic.Compare(expectedResult, actualResult);
    Console.WriteLine($"Are the sequences equivalent: {comparisonResult.AreEqual}");
    Console.WriteLine(expectedResult);
    Console.WriteLine(actualResult);
}

public class SUT
{
    IMapper _mapper;
    PipelineContext _pipelineContext;

    public SUT(IMapper mapper, PipelineContext pipelineContext)
    {
        _pipelineContext = pipelineContext;
        _mapper = mapper;
    }

    public async Task<List<BusinessEntity>> Handle()
    {
        return await _mapper.ProjectTo<BusinessEntity>(_pipelineContext.Entities).ToListAsync();
    }
}

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

    public virtual DbSet<DataEntity> Entities { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<DataEntity>().HasNoKey().ToView(nameof(DataEntity));
    }
}

public class MappingProfile : Profile
{
    public MappingProfile()
    {
        CreateMap<DataEntity, BusinessEntity>()
        .ForMember(d => d.id, o => o.MapFrom(s => s.Id))
        .ForMember(d => d.code, o => o.MapFrom(s => s.Code))
        .ReverseMap();
    }
}

public class DataEntity
{
    public Guid Id { get; set; }

    public string Code { get; set; }
}

public class BusinessEntity
{
    public Guid id { get; set; }

    public string code { get; set; }
}

这个returns:

显然，在没有最小可重现示例的情况下，我已经对此进行了简化，但这不应该改变方法。我假设该集合是基于属性名称（查询）的 read-only，因此使用 AddToReadOnlySource 进行排列。如果不是 read-only，您将改用 AddRange。

模拟映射器。

根据 JBogard 对该主题的评论，我大部分时间都使用真实的映射器。但是，您似乎愿意模拟它，您可以简单地将 ProjectTo 调用模拟为 return 所需的 IAsyncEnumerable 序列：

void Main()
{
    var fixture = new Fixture();
    
    var dataEntites = new AsyncEnumerable<DataEntity>(fixture.CreateMany<DataEntity>());
    var expectedResult = new AsyncEnumerable<BusinessEntity>(dataEntites.Select(x => new BusinessEntity() { id = x.Id, code = x.Code }));

    var mapperMock = new Mock<IMapper>();
    mapperMock.Setup(x => x.ProjectTo<BusinessEntity>(It.IsAny<IQueryable<DataEntity>>(), It.IsAny<object>())).Returns(expectedResult);
    var mapper = mapperMock.Object;

    var sut = new SUT(mapper);

    var actualResult = sut.Handle(dataEntites).Result;

    var compareLogic = new CompareLogic();
    compareLogic.Config.IgnoreObjectTypes = true;
    compareLogic.Config.IgnoreCollectionOrder = true;
    var comparisonResult = compareLogic.Compare(expectedResult, actualResult);
    Console.WriteLine($"Are the sequences equivalent: {comparisonResult.AreEqual}");
    Console.WriteLine(expectedResult);
    Console.WriteLine(actualResult);
}

public class SUT
{
    IMapper _mapper;

    public SUT(IMapper mapper)
    {
        _mapper = mapper;
    }

    public async Task<List<BusinessEntity>> Handle(IQueryable<DataEntity> entities)
    {
        return await _mapper.ProjectTo<BusinessEntity>(entities).ToListAsync();
    }
}

public class DataEntity
{
    public Guid Id { get; set; }

    public string Code { get; set; }
}

public class BusinessEntity
{
    public Guid id { get; set; }

    public string code { get; set; }
}

结果：

这使用了 AsyncEnumerable class from EntityFrameworkCore.Testing，您可以按原样使用它，也可以根据需要将其作为您自己实施的基础。

.Net Core 单元测试错误 - 源 IQueryable 未实现 IAsyncEnumerable<...>

.Net Core Unit Test Error - The source IQueryable doesn't implement IAsyncEnumerable<...>

c#

unit-testing

moq

automapper

.net-core-3.1