在测试中使用 MediatR 时无法访问已处理的对象 (IServiceProvider)

Question

我收到以下错误：

Cannot access a disposed object.
Object name: 'IServiceProvider'.

尝试调用 _mediator.Send 方法时。

这仅在我尝试测试控制器的方法时发生。每当从 api 调用控制器时，它似乎都能正常工作。

控制器：

public class Controller : ControllerBase
{
    private readonly IMediator mediator;
    public Controller(IMediator mediator)
    {
        this.mediator = mediator;
    }

    [HttpPost]
    public async Task<IActionResult> Post(Command command)
    {
        try
        {
            await mediator.Send(command); // exception occurs here
            return Ok();

        }
        catch (Exception ex)
        {
            return BadRequest(ex.InnerException?.Message ?? ex.Message);
        }
    }
}

请求处理器：

  public class CommandHandler
    : IRequestHandler<Command, bool>
    {
        private readonly AppDbContext dbContext;
        public CommandHandler(AppDbContext dbContext)
        {
            this.dbContext = dbContext;
        }
        public async Task<bool> Handle(Command request, CancellationToken cancellationToken)
        {
            try
            {
                await dbContext.Companies.AddAsync(new Company(request.CompanyId, request.CompanyName), cancellationToken);
                await dbContext.SaveChangesAsync(cancellationToken);
                return true;
            }
            catch(Exception)
            {
                throw;
            }
        }
    }

MediatR 是这样注册的：

services.AddMediatR(Assembly.GetExecutingAssembly());

我正在尝试使用真实的数据库连接来测试这个控制器。

protected Controller GetController() // method where controller is created and mediatR injected
{
    using var scope = _scopeFactory.CreateScope();
    var mediator = scope.ServiceProvider.GetRequiredService<IMediator>();
    return new Controller(mediator);
}



protected async Task<IActionResult> PostControllerMethod(Command command) // this method is call in test method
    => await GetController().Post(command);

解决问题的唯一方法是将 MediatR 注册为单例：

   services.AddMediatR(mediatRServiceConfiguration => mediatRServiceConfiguration.AsSingleton(), Assembly.GetExecutingAssembly());

我不确定后果。