如何对 ActionFilterAttribute 进行单元测试答案

【问题标题】：How to unit test ActionFilterAttribute如何对 ActionFilterAttribute 进行单元测试
【发布时间】：2018-02-20 02:56:42
【问题描述】：

我正在寻找在 .NET Core 2.0 API 项目中测试 ActionFilterAttribute 并想知道最好的方法。请注意，我不是试图通过控制器操作来测试它，只是测试 ActionFilterAttribute 本身。

我该如何进行测试：

    public class ValidateModelAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            if (!context.ModelState.IsValid)
            {
                context.Result = new BadRequestObjectResult(context.ModelState);
            }
        }
    }

【问题讨论】：

标签： unit-testing .net-core xunit xunit.net actionfilterattribute

【解决方案1】：

创建上下文的实例，将其传递给过滤器并断言预期的行为

例如

[TestClass]
public class ValidateModelAttributeTest {
    [TestMethod]
    public void Invalid_ModelState_Should_Return_BadRequestObjectResult() {
        //Arrange
        var modelState = new ModelStateDictionary();
        modelState.AddModelError("", "error");
        var httpContext = new DefaultHttpContext();
        var context = new ActionExecutingContext(
            new ActionContext(
                httpContext: httpContext,
                routeData: new RouteData(),
                actionDescriptor: new ActionDescriptor(),
                modelState: modelState
            ),
            new List<IFilterMetadata>(),
            new Dictionary<string, object>(),
            new Mock<Controller>().Object);

        var sut = new ValidateModelAttribute();

        //Act
        sut.OnActionExecuting(context);

        //Assert
        context.Result.Should().NotBeNull()
            .And.BeOfType<BadRequestObjectResult>();
    }
}

【讨论】：

感谢您的回复。在接受了帮助后发现了这个：stackoverflow.com/questions/36629391/…
@nkosi 快速问：当我尝试上面的代码时，ModelState 是有效的。有没有技巧可以让 modelState 处于无效状态？我们是否需要创建一些虚假的路线之类的？
@Pure.Krome 您需要在模型状态字典中添加模型错误以使其无效。
我只返回“null”，有什么建议吗？
@FrankR.Haugen 你的哪一部分是空的

【解决方案2】：

这是一个真实的例子，我还可以访问 action filter 属性中的方法信息和参数：

假设我有一个带有 ActionAttribute 的控制器方法，如下所示：

 public class HomeController : Controller
    {
    ...
    [FeatureFlagActionAtrribute("user", new String[] { "Feature1" })]
    public IActionResult DoSomethingWithFilterAction(String user)
        {...}
    }

http 调用是这样的：

/Home/DoSomethingWithFilterAction?user="user1"

现在，我想在这样的上下文中测试 ActionAttribute FeatureFlagActionAtrribute。

如果您将上述建议应用于此示例，它看起来像这样（至少对我有用）

 var methodInfoDoSomethingWithFilterAction = typeof(HomeController).GetMethod(nameof(HomeController.DoSomethingWithFilterAction));
    var httpContext = new DefaultHttpContext();
    var routeData = new RouteData();
    FeatureFlagActionAtrribute FeatureFlagActionAtrributeFilter = methodInfoDoSomethingWithFilterAction.GetCustomAttribute<FeatureFlagActionAtrribute>();
    ActionDescriptor actionDescriptor = new ControllerActionDescriptor()
                {
                    ActionName = methodInfoDoSomethingWithFilterAction.Name,
                    ControllerName = typeof(FeatureFlagTest).Name,
                    DisplayName = methodInfoDoSomethingWithFilterAction.Name,
                    MethodInfo = methodInfoDoSomethingWithFilterAction,
                };

    ActionContext actionContext = new ActionContext(httpContext, routeData, actionDescriptor) ;
    var homeController = new HomeController();
    var attribute = new FeatureFlagActionAtrribute("user", new string[] { "feature1" });
    IDictionary<string, object> actionArguments = new Dictionary<string, object>
                {
                    ["user"] = "user1"
                };

    var filterMetadata = new List<IFilterMetadata>() { featureFlagActionAtrributeFilter };

    ActionExecutingContext actionExecutedContext = new 
    ActionExecutingContext(actionContext, filterMetadata, actionArguments, homeController);


    attribute.OnActionExecuting(actionExecutedContext);

然后在ActionFilterAttribute里面：

public override void OnActionExecuting(ActionExecutingContext context)
{
        ControllerActionDescriptor actionDescriptor = (ControllerActionDescriptor)context.ActionDescriptor;
        Debug.Print($"2. @Before Method called {actionDescriptor.ControllerName}Controller.{actionDescriptor.ActionName}");
        var controllerName = actionDescriptor.ControllerName;
        var actionName = actionDescriptor.ActionName;
        IDictionary<object, object> properties = actionDescriptor.Properties;
        ParameterInfo[] paramsOfMethod = actionDescriptor.MethodInfo.GetParameters();
        var fullName = actionDescriptor.DisplayName;

        var paramNameForKeyOfFeature = ParamNameForKeyOfFeature;

        var arguments = context.ActionArguments;

【讨论】：