c# - 如何使用 ASP.NET CORE Razor Page Web App 中涉及的 TryUpdateModelAsync 对方法进行单元测试？

Question

TryUpdateModelAsync 是抽象类 PageModel 的一个内部保护方法，在我看来，这使得它不可模拟。是否有任何方法可以对涉及此方法的任何操作进行单元测试？

我在网上看到这个解决方案: asp.net core mvc controller unit testing when using TryUpdateModel .

但是，它只适用于 ASP.NET Core MVC Web App，因为 TryUpdateModelAsync 是一个公共(public)方法，所以我们可以添加一个适配器来包装这个方法，让我们的适配器调用实际的方法。在 Razor 页面中，无法从外部访问此 TryUpdateModelAsync。

我现在遇到的问题是当我对 OnPostAsync 方法进行单元测试时，TryUpdateModelAsync总是抛出异常。我永远无法通过那条线来检查它之后的代码逻辑。

所以这是我要进行单元测试的操作:

 public class CreateModel : PageModel
    {
     //elided
        [BindProperty]
        public Post Post { get; set; }

        public async Task<IActionResult> OnPostAsync()
        {
            if (!ModelState.IsValid)
            {
                return Page();
            }
            if (await TryUpdateModelAsync<Post>(Post, "Post", p => p.Title, p => p.SubTitle, p => p.Author, p => p.Content, p => p.CategoryID)){
                //do stuff
                return RedirectToPage("./Index");
            }
            //do stuff
            return Page();
        }

这是我为它编写的单元测试:

  [Test]
  public async Task InvokeOnPostAsyncWithInvalidModelState_ShouldReturnPageResultType(){
            //Arrange
            InitPostModelProperties();
            var createModel = new CreateModel(){
                PageContext = _pageContext,
                TempData = _tempData,
                Url = _urlHelper
            };
           //do arrangement

            //Act
            var result = await createModel.OnPostAsync();

            //Assert
        }

更新:

下面是我为这个测试所做的完整初始化过程:

  public void InitPostModelProperties(){
 _httpContext = new DefaultHttpContext(){
                //RequestServices = services.BuildServiceProvider()
            };
            _modelStateDictionary = new ModelStateDictionary();
            _modelMetaDataProvider = new EmptyModelMetadataProvider();
            _actionContext = new ActionContext(_httpContext, new RouteData(), new PageActionDescriptor(), _modelStateDictionary);
            _viewData = new ViewDataDictionary(_modelMetaDataProvider, _modelStateDictionary);
            _tempData = new TempDataDictionary(_httpContext, Mock.Of<ITempDataProvider>());
            _pageContext = new PageContext(_actionContext){
                ViewData = _viewData
            };
            _urlHelper = new UrlHelper(_actionContext);
        }

然后我收到以下异常消息:

  Error Message:
   System.ArgumentNullException : Value cannot be null.
Parameter name: metadataProvider
  Stack Trace:
     at Microsoft.AspNetCore.Mvc.ModelBinding.Internal.ModelBindingHelper.TryUpdateModelAsync(Object model, Type modelType, String prefix, ActionContext actionContext, IModelMetadataProvider metadataProvider, IModelBinderFactory modelBinderFactory, IValueProvider valueProvider, IObjectModelValidator objectModelValidator, Func`2 propertyFilter)
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.TryUpdateModelAsync[TModel](TModel model, String name, Expression`1[] includeExpressions)

然后我将初始化更改为以下内容:

  public void InitPostModelProperties(){
  var services = new ServiceCollection();
  services.AddTransient<IModelMetadataProvider, ModelMetadataProvider>();
 _httpContext = new DefaultHttpContext(){
                RequestServices = services.BuildServiceProvider()
            };
            _modelStateDictionary = new ModelStateDictionary();
            _modelMetaDataProvider = new EmptyModelMetadataProvider();
            _actionContext = new ActionContext(_httpContext, new RouteData(), new PageActionDescriptor(), _modelStateDictionary);
            _viewData = new ViewDataDictionary(_modelMetaDataProvider, _modelStateDictionary);
            _tempData = new TempDataDictionary(_httpContext, Mock.Of<ITempDataProvider>());
            _pageContext = new PageContext(_actionContext){
                ViewData = _viewData
            };
            _urlHelper = new UrlHelper(_actionContext);
        }

然后我得到了新的异常信息:

Outcome: Failed
    Error Message:
    System.InvalidOperationException : No service for type 'Microsoft.AspNetCore.Mvc.ModelBinding.IModelMetadataProvider' has been registered.
    Stack Trace:
       at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.get_MetadataProvider()
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.TryUpdateModelAsync[TModel](TModel model, String name, Expression`1[] includeExpressions)

我按照异常消息添加了这些行:

services.AddSingleton<IModelMetadataProvider, EmptyModelMetadataProvider>();

收到新的异常消息:

  Outcome: Failed
    Error Message:
    System.InvalidOperationException : No service for type 'Microsoft.AspNetCore.Mvc.ModelBinding.IModelBinderFactory' has been registered.
    Stack Trace:
       at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.get_ModelBinderFactory()
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.TryUpdateModelAsync[TModel](TModel model, String name, Expression`1[] includeExpressions)

我一直在添加新行:

 services.AddSingleton<IModelBinderFactory,ModelBinderFactory>();

才发现服务无法实例化，因为ModelBinderFactory类是抽象类

我被困在这里了。

更新

整个测试代码如下:

源代码:

  public class BaseTests
    {
        private  HugoBlogContext _context;

        public HugoBlogContext Context => _context;
        public List<Category> CatList;
        public List<Post> PostList;

        public List<Tag> TagList;

        public List<PostTag> PostTagList;

        public BaseTests(){}


 public class PageModelBaseTests: BaseTests
    {
        protected ICategoryRepository _categoryRepository;

        protected IPostRepository _postRepository;

        protected IPostTagRepository _postTagRepository;

        protected ITagRepository _tagRepository;

        protected ISelectTagService _selectTagService;

        protected IDropdownCategoryService _dropdownCategoryService;

        protected HttpContext _httpContext;

        protected ModelStateDictionary _modelStateDictionary;

        protected ActionContext _actionContext;

        protected ModelMetadataProvider _modelMetaDataProvider;

        protected ViewDataDictionary _viewData;

        protected TempDataDictionary _tempData;

        protected PageContext _pageContext;

        protected UrlHelper _urlHelper;



        [SetUp]
        public void Init(){
            _categoryRepository = new CategoryRepository(Context);
            _postRepository = new PostRepository(Context);
            _postTagRepository = new PostTagRepository(Context);
            _tagRepository = new TagRepository(Context);
            _selectTagService = new SelectTagService(_tagRepository, _postRepository, _postTagRepository);
            _dropdownCategoryService = new DropdownCategoryService(_categoryRepository);
        }


        public void InitPostModelProperties(){
            var services = new ServiceCollection();
            services.AddSingleton<IModelMetadataProvider, EmptyModelMetadataProvider>();
            services.AddSingleton<IModelBinderFactory,ModelBinderFactory>();
            _httpContext = new DefaultHttpContext(){
                RequestServices = services.BuildServiceProvider()
            };
            _modelStateDictionary = new ModelStateDictionary();
            _modelMetaDataProvider = new EmptyModelMetadataProvider();
            _actionContext = new ActionContext(_httpContext, new RouteData(), new PageActionDescriptor(), _modelStateDictionary);
            _viewData = new ViewDataDictionary(_modelMetaDataProvider, _modelStateDictionary);
            _tempData = new TempDataDictionary(_httpContext, Mock.Of<ITempDataProvider>());
            _pageContext = new PageContext(_actionContext){
                ViewData = _viewData
            };
            _urlHelper = new UrlHelper(_actionContext);
        }


[TestFixture]
  public class CreateModelTests: PageModelBaseTests
    {

[Test]
    public async Task InvokeOnPostAsyncWithValidModelState_ShouldReturnRedirectPageResultTypeAndCategoryShouldBeUpdated(){
              //Arrange
            InitPostModelProperties();
            var createModel = new CreateModel(_selectTagService, _dropdownCategoryService ,_postRepository){
                PageContext = _pageContext,
                TempData = _tempData,
                Url = _urlHelper,
            };
            createModel.Post = new Post{
                Title = "Create",
                SubTitle = "Create",
                Content = "Create",
                Author = "Create",
                CategoryID = CatList.Count + 1,
            };
            var selectedTags = new string[3]{"4","5","6"};

            //Act
            var result = await createModel.OnPostAsync(selectedTags);

            //Assert
            result.Should().BeOfType<RedirectToPageResult>();
            Context.Posts.Where(c => c.CategoryID == (CatList.Count + 1)).Should().NotBeNull();
        }
    }

更新模拟后，我收到以下异常消息:

  Outcome: Failed
    Error Message:
    System.NullReferenceException : Object reference not set to an instance of an object.
    Stack Trace:
       at Microsoft.AspNetCore.Mvc.ModelBinding.Internal.ModelBindingHelper.TryUpdateModelAsync(Object model, Type modelType, String prefix, ActionContext actionContext, IModelMetadataProvider metadataProvider, IModelBinderFactory modelBinderFactory, IValueProvider valueProvider, IObjectModelValidator objectModelValidator, Func`2 propertyFilter)
   at Microsoft.AspNetCore.Mvc.RazorPages.PageModel.TryUpdateModelAsync[TModel](TModel model, String name, Expression`1[] includeExpressions)

仅供引用:我还 mock 了IObjectValidator通过使用 services.AddSingleton<IObjectValidator>(Mock.Of<IObjectValidator>())

Answer 1

我不确定测试 TryValidateModel 或 TryUpdateModelAsync 是我们的责任；可以安全地假设框架方法是正确的，对吧。

另一个论点是您正在测试您的实现而不是其他人的。

无论如何，如果你想忽略这些方法，你可以在你的测试方法中尝试这个(我正在使用 Moq 作为我的模拟框架)完全忽略这些方法并且实际上假设它们是正确的:

var objectModelValidatorMock = new Mock<IObjectModelValidator>();
objectModelValidatorMock
    .Setup(o => o.Validate(
        It.IsAny<ActionContext>(),
        It.IsAny<ValidationStateDictionary>(),
        It.IsAny<string>(),
        It.IsAny<object>()));

var sut = new NewController
{
    ObjectValidator = objectModelValidatorMock.Object
};