如何在 ASP.NET Core 中对 ViewBag 进行单元测试？

Question

在为 ASP.NET 核心应用程序编写单元测试时，我意识到 ViewData 可以从 ViewResult 访问，但 ViewBag 不能。

我的HomeController:

public class HomeController : Controller
{
    private readonly IHeroRepository _heroItems;
    private readonly IQuestRepository _questItems;

    public HomeController(
        IHeroRepository heroItems,
        IQuestRepository questItems)
    {
        _heroItems = heroItems;
        _questItems = questItems;
    }

    [HttpGet]
    public async Task<IActionResult> Index()
    {
        var recentHeroesVM = await _heroItems.GetRecentHeroesAsync(2);
        ViewBag.QuestSelectList = await _questItems.GetSelectListAsync();
        return View(recentHeroesVM);
    }
}

我的测试class:

public class HomeController_Index
{
    [Fact]
    public async Task Index_ReturnsAViewResult_WithAListOfRecentHeros()
    {
        // Arrange
        var mockHeroRepo = new Mock<IHeroRepository>();
        var mockQuestRepo = new Mock<IQuestRepository>();
        var recentHerosCount = 2;
        mockHeroRepo.Setup
        (
            repo => repo.GetRecentHerosAsync(recentHerosCount))
                .Returns(Task.FromResult(GetTestItems())
        );
        var controller = new HomeController(mockHeroRepo.Object, mockQuestRepo.Object);

        // Act
        var result = await controller.Index();

        // Assert
        var viewResult = Assert.IsType<ViewResult>(result);

        // No definition error below.
        var questSelectListVB = Assert.IsAssignableFrom<SelectList>(
            viewResult.ViewBag.QuestSelectList);
    }

    private IEnumerable<HeroViewModel> GetTestItems()
    {
        var items = new List<HeroViewModel>
        {
            new HeroViewModel
            {
                Name = "First Hero",
            },
            new HeroViewModel
            {
                Name = "Second Hero",
            },
        };
        return items;
    }
}

问题1：为什么在ASP.NETMVC版本ViewResult中没有ViewBag属性ViewResult class 明明有一个(MSDN)？

问题 2： 当我无法访问 ViewBag 时，我应该如何测试它？

Answer 1

问题一：对我来说还是个谜。更像是核心开发人员的问题。

问题二：

"The ViewBag property is a wrapper around ViewData that provides a dynamic view over that collection. It is not a separate collection." - ASP.NET Core Docs

所以它是一个对象。由于 ViewResult 中没有 ViewBag 属性（提醒 - 我们在这里谈论的是 Core 版本），因此在 ViewData 字典样式中访问它：

var questSelectListVB = Assert.IsAssignableFrom<SelectList>(viewResult.ViewData["QuestSelectList"]);

如何在 ASP.NET Core 中对 ViewBag 进行单元测试？

How to unit test ViewBag in ASP.NET Core?

c#

unit-testing

asp.net-core

xunit

viewbag