我打算写一个ActionFilter用于业务验证，其中一些服务将通过Service Locator解决（我知道这不是一个好的做法，我尽可能避免服务定位器模式，但为此我想用它）。
OnActionExecuting方法是这样的：
public override void OnActionExecuting(ActionExecutingContext actionContext)
{
// get validator for input;
var validator = actionContext.HttpContext.RequestServices.GetService<IValidator<TypeOfInput>>();// i will ask another question for this line
if(!validator.IsValid(input))
{
//send errors
}
}
是否可以为上述ActionFilter以及如何编写单元测试？
答案 0 :(得分：7)
以下是有关如何创建模拟（使用XUnit和Moq框架）以验证调用IsValid方法以及模拟返回false的位置的示例。
using Dealz.Common.Web.Tests.Utils;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.DependencyInjection;
using Moq;
using System;
using Xunit;
namespace Dealz.Common.Web.Tests.ActionFilters
{
public class TestActionFilter
{
[Fact]
public void ActionFilterTest()
{
/****************
* Setup
****************/
// Create the userValidatorMock
var userValidatorMock = new Mock<IValidator<User>>();
userValidatorMock.Setup(validator => validator
// For any parameter passed to IsValid
.IsValid(It.IsAny<User>())
)
// return false when IsValid is called
.Returns(false)
// Make sure that `IsValid` is being called at least once or throw error
.Verifiable();
// If provider.GetService(typeof(IValidator<User>)) gets called,
// IValidator<User> mock will be returned
var serviceProviderMock = new Mock<IServiceProvider>();
serviceProviderMock.Setup(provider => provider.GetService(typeof(IValidator<User>)))
.Returns(userValidatorMock.Object);
// Mock the HttpContext to return a mockable
var httpContextMock = new Mock<HttpContext>();
httpContextMock.SetupGet(context => context.RequestServices)
.Returns(serviceProviderMock.Object);
var actionExecutingContext = HttpContextUtils.MockedActionExecutingContext(httpContextMock.Object, null);
/****************
* Act
****************/
var userValidator = new ValidationActionFilter<User>();
userValidator.OnActionExecuting(actionExecutingContext);
/****************
* Verify
****************/
// Make sure that IsValid is being called at least once, otherwise this throws an exception. This is a behavior test
userValidatorMock.Verify();
// TODO: Also Mock HttpContext.Response and return in it's Body proeprty a memory stream where
// your ActionFilter writes to and validate the input is what you desire.
}
}
class User
{
public string Username { get; set; }
}
class ValidationActionFilter<T> : IActionFilter where T : class, new()
{
public void OnActionExecuted(ActionExecutedContext context)
{
throw new NotImplementedException();
}
public void OnActionExecuting(ActionExecutingContext actionContext)
{
var type = typeof(IValidator<>).MakeGenericType(typeof(T));
var validator = (IValidator<T>)actionContext.HttpContext
.RequestServices.GetService<IValidator<T>>();
// Get your input somehow
T input = new T();
if (!validator.IsValid(input))
{
//send errors
actionContext.HttpContext.Response.WriteAsync("Error");
}
}
}
internal interface IValidator<T>
{
bool IsValid(T input);
}
}
HttpContextUtils.cs
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using System.Collections.Generic;
namespace Dealz.Common.Web.Tests.Utils
{
public class HttpContextUtils
{
public static ActionExecutingContext MockedActionExecutingContext(
HttpContext context,
IList<IFilterMetadata> filters,
IDictionary<string, object> actionArguments,
object controller
)
{
var actionContext = new ActionContext() { HttpContext = context };
return new ActionExecutingContext(actionContext, filters, actionArguments, controller);
}
public static ActionExecutingContext MockedActionExecutingContext(
HttpContext context,
object controller
)
{
return MockedActionExecutingContext(context, new List<IFilterMetadata>(), new Dictionary<string, object>(), controller);
}
}
}
正如您所看到的，它非常混乱，您需要创建大量的模拟来模拟实际类的不同响应，只是为了能够单独测试ActionAttribute。
答案 1 :(得分：7)
我喜欢@Tseng的上述答案，但考虑给出更多答案，因为他的答案涵盖了更多场景（如泛型），并且可能会让一些用户感到压力。
这里我有一个动作过滤器属性，它通过在上下文中设置ModelState属性来检查Result和短路（在没有调用动作的情况下返回响应）请求。在过滤器中，我尝试使用ServiceLocator模式来获取记录器来记录一些数据（有些可能不喜欢这个，但这是一个例子）
过滤
public class ValidationFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext context)
{
if (!context.ModelState.IsValid)
{
var logger = context.HttpContext.RequestServices.GetRequiredService<ILogger<ValidationFilterAttribute>>();
logger.LogWarning("some message here");
context.Result = new JsonResult(new InvalidData() { Message = "some messgae here" })
{
StatusCode = 400
};
}
}
}
public class InvalidData
{
public string Message { get; set; }
}
单元测试
[Fact]
public void ValidationFilterAttributeTest_ModelStateErrors_ResultInBadRequestResult()
{
// Arrange
var serviceProviderMock = new Mock<IServiceProvider>();
serviceProviderMock
.Setup(serviceProvider => serviceProvider.GetService(typeof(ILogger<ValidationFilterAttribute>)))
.Returns(Mock.Of<ILogger<ValidationFilterAttribute>>());
var httpContext = new DefaultHttpContext();
httpContext.RequestServices = serviceProviderMock.Object;
var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
var actionExecutingContext = new ActionExecutingContext(
actionContext,
filters: new List<IFilterMetadata>(), // for majority of scenarios you need not worry about populating this parameter
actionArguments: new Dictionary<string, object>(), // if the filter uses this data, add some data to this dictionary
controller: null); // since the filter being tested here does not use the data from this parameter, just provide null
var validationFilter = new ValidationFilterAttribute();
// Act
// Add an erorr into model state on purpose to make it invalid
actionContext.ModelState.AddModelError("Age", "Age cannot be below 18 years.");
validationFilter.OnActionExecuting(actionExecutingContext);
// Assert
var jsonResult = Assert.IsType<JsonResult>(actionExecutingContext.Result);
Assert.Equal(400, jsonResult.StatusCode);
var invalidData = Assert.IsType<InvalidData>(jsonResult.Value);
Assert.Equal("some messgae here", invalidData.Message);
}