ASP.NET Core Integration Test for controller action - asp.net-core

Question

Microsoft documentation (https://learn.microsoft.com/en-us/aspnet/core/testing/integration-testing) explain how to implement an integration test using the TestServer class. It is easy in case we are using WEB API because we get the serialized model as response from the action.
But in case I want to test a Controller action returning an HTML View containing some data, how can I evaluate that the page content is what I expect (avoiding to scan the HTML page contents) ?

Answer 1

One option is to use Automated UI Testing using something like Selenium

Answer 2

In order to append this JSON serialized view model to your page, I implemented the following filter:
using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Newtonsoft.Json;
using Ticketino.Web.Components.Extensions.Request;
using Ticketino.Web.OnlineShop.Serializations;
using Ticketino.Web.OnlineShop.ViewModels.Base;
namespace Ticketino.Web.OnlineShop.Filters
{
/// <summary>
/// This is a filter used only for integration tests.
/// It format the ViewModel as jSon and appends it to the end of HMTL page, so that it can be deserialized from the test in order to check its values.
/// </summary>
/// <seealso cref="Microsoft.AspNetCore.Mvc.Filters.ResultFilterAttribute" />
[AttributeUsage(AttributeTargets.Method)]
public class IntegrationTestFilterAttribute : ResultFilterAttribute
{
public const string StartViewModelContainer = "<script type=\"model/json\">";
public const string EndViewModelContainer = "</script>";
public override void OnResultExecuting(ResultExecutingContext filterContext)
{
if (!filterContext.ModelState.IsValid)
{
var viewResult = filterContext.Result as ViewResult;
if (viewResult?.Model is BaseViewModel)
{
var errors = IntegrationTestFilterAttribute.GetModelErrors(filterContext.ModelState);
((BaseViewModel)viewResult.Model).ValidationErrors = errors;
}
}
base.OnResultExecuting(filterContext);
}
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
if (!filterContext.HttpContext.Request.IsAjaxRequest())
{
var viewResult = filterContext.Result as ViewResult;
if (viewResult?.Model != null)
{
var jsonViewModel = string.Concat(
IntegrationTestFilterAttribute.StartViewModelContainer,
JsonConvert.SerializeObject(viewResult.Model, Formatting.None, CommonJsonSerializerSettings.Settings()),
IntegrationTestFilterAttribute.EndViewModelContainer);
filterContext.HttpContext.Response.WriteAsync(jsonViewModel);
}
}
base.OnResultExecuted(filterContext);
}
#region Private methods
private static IDictionary<string, string> GetModelErrors(ModelStateDictionary errDictionary)
{
var errors = new Dictionary<string, string>();
//get all entries from the ModelStateDictionary that have any errors and add them to our Dictionary
errDictionary.Where(k => k.Value.Errors.Count > 0).ForEach(i =>
{
foreach (var errorMessage in i.Value.Errors.Select(e => e.ErrorMessage))
{
errors.Add(i.Key, errorMessage);
}
});
return errors;
}
#endregion
}
}
Then, in ConfigureServices(IServiceCollection serviceCollection) method inject it when you run integration test as show:
// Filter to append json serialized view model to buttom html response page, in order to eveluate from integration test class
if (_hostingEnvironment.IsIntegrationTest())
{
mvcBuilder.AddMvcOptions(opt => { opt.Filters.Add(new IntegrationTestFilterAttribute()); });
}