如何用 Moq 模拟 ActionExecutingContext？答案

【问题标题】：How to mock ActionExecutingContext with Moq?如何用 Moq 模拟 ActionExecutingContext？
【发布时间】：2016-08-06 09:05:02
【问题描述】：

我正在尝试测试以下过滤器：

using Microsoft.AspNet.Mvc;
using Microsoft.AspNet.Mvc.Filters;

namespace Hello
{
    public class ValidationFilter : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            if (!filterContext.ModelState.IsValid) {
                filterContext.Result = new BadRequestObjectResult(filterContext.ModelState);
            }
        }
    }
}

我正在尝试使用 Moq 模拟 ActionFilterAttribute。

我正在使用 Mvc 6.0.0-rc1

我的第一次尝试：

var context = new ActionExecutingContext(
                    new ActionContext(Mock.Of<HttpContext>(), new RouteData(), new ActionDescriptor()),
                    new IFilterMetadata[] { filter, },
                    new Dictionary<string, object>(),
                    controller: new object());

但我无法覆盖 ModelState。它看起来是只读的：https://github.com/aspnet/Mvc/blob/6.0.0-rc1/src/Microsoft.AspNet.Mvc.Abstractions/ActionContext.cs#L25

然后我尝试了：

var contextMock = new Mock<ActionExecutingContext>(
                    new ActionContext(Mock.Of<HttpContext>(), new RouteData(), new ActionDescriptor()),
                    new IFilterMetadata[] { filter, },
                    new Dictionary<string, object>());

但是当我打电话给filter.OnActionExecuting(contextMock.Object) 时，我收到以下错误：

Castle.DynamicProxy.InvalidProxyConstructorArgumentsException : Can not instantiate proxy of class: Microsoft.AspNet.Mvc.Filters.ActionExecutingContext.
      Could not find a constructor that would match given arguments:
      Microsoft.AspNet.Mvc.ActionContext
      Microsoft.AspNet.Mvc.Filters.IFilterMetadata[]
      System.Collections.Generic.Dictionary`2[System.String,System.Object]

如何测试使用 ModelState 的过滤器？

【问题讨论】：

标签： asp.net-mvc unit-testing moq xunit

【解决方案1】：

我只是偶然发现了同样的问题并以这种方式解决了它。

[Fact]
public void ValidateModelAttributes_SetsResultToBadRequest_IfModelIsInvalid()
{
    var validationFilter = new ValidationFilter();
    var modelState = new ModelStateDictionary();
    modelState.AddModelError("name", "invalid");

    var actionContext = new ActionContext(
        Mock.Of<HttpContext>(),
        Mock.Of<RouteData>(),
        Mock.Of<ActionDescriptor>(),
        modelState
    );

    var actionExecutingContext = new ActionExecutingContext(
        actionContext,
        new List<IFilterMetadata>(),
        new Dictionary<string, object>(),
        Mock.Of<Controller>()
    );

    validationFilter.OnActionExecuting(actionExecutingContext);

    Assert.IsType<BadRequestObjectResult>(actionExecutingContext.Result);
}

【讨论】：

一些用法：using System;使用 System.Net；使用 Microsoft.AspNetCore.Mvc；使用 Microsoft.AspNetCore.Mvc.Filters;

【解决方案2】：

如果有人想知道当您从 IAsyncActionFilter 继承时如何做到这一点

[Fact]
public async Task MyTest()
{
    var modelState = new ModelStateDictionary();

    var httpContextMock = new DefaultHttpContext();

    httpContextMock.Request.Query = new QueryCollection(new Dictionary<string, StringValues> {}); // if you are reading any properties from the query parameters

    var actionContext = new ActionContext(
        httpContextMock,
        Mock.Of<RouteData>(),
        Mock.Of<ActionDescriptor>(),
        modelState
    );

    var actionExecutingContext = new ActionExecutingContext(
        actionContext,
        new List<IFilterMetadata>(),
        new Dictionary<string, object>(),
        Mock.Of<Controller>()
    )
    {
        Result = new OkResult() // It will return ok unless during code execution you change this when by condition
    };

    Mymock1.SetupGet(x => x.SomeProperty).Returns("MySomething");
    Mymock2.Setup(x => x.GetSomething(It.IsAny<string>(), It.IsAny<string>())).ReturnsAsync(true);

    var context = new ActionExecutedContext(actionContext, new List<IFilterMetadata>(), Mock.Of<Controller>());

    await _classUnderTest.OnActionExecutionAsync(actionExecutingContext, async () => { return context; });

    actionExecutingContext.Result.Should().BeOfType<OkResult>();
}

【讨论】：