自动映射器无法异步映射

Question

我有一个异步方法：

public async Task<TProjection> GetById<TProjection>(int id)
{
    return await Collection
        .Where(entity => entity.Id == id)
        .ProjectTo<TProjection>()
        .ToListAsync();
}

我需要进行单元测试，这要归功于answer here

但是，尝试投影到TestEntity会导致抛出以下异常：

Unable to cast object of type 'TestDbAsyncEnumerable'1[Models.Entity]' to type 'System.Linq.IQueryable'1[TestSpecNamespace+TestEntity]'.

以下是测试：

[Theory]//And then a bunch of ids
public async Task GetSubEntities_Projects_IdExists(int id)
{
    Mapper.Initialize(cfg => { cfg.CreateMap<Entity, TestEntity>(); });
    var mockContext = CreateMockContext();
    var provider = TestProvider.Create(context: mockContext.Object);

    var response = await provider.GetById<TestEntity>(id); //Calls the aforementioned

    //Asserts
}