Asp.Net Core 2.0 Xunit Tests

Question

I am new .asp.net core. I am testing a controller that renders a view to a string and then utilises evo pdf to render the view.

All is working perfectly and I am also able to successfully test using postman. However my test app errors when I use vs 2017 test explorer to debug my test (Xunit). Searched Locations within the razor engine The error occurs within my RenderViewToString method as my razor view engine is unable to locate the view to render. The paths searched to locate the views are as expected. Any guidance is appreciated.

    //Unit Test Code
    [Fact]
    public async void GetPdf()
    {
        var response = await _client.PostAsJsonAsync<Common.DTO.Invoice>("/api/values/1", GetDummyData());

        using (var file = System.IO.File.Create(@"c:\\Test" + DateTime.Now.ToString("yyyyyMMddHHmmss") + ".pdf"))
            {
            //create a new file to write to
            await response.Content.CopyToAsync(file);
            await file.FlushAsync(); // flush back to disk before disposing
            }


    }

    //Render view to string service
    public interface IViewRenderService
    {
    Task<string> RenderToStringAsync(string viewName, ViewDataDictionary viewData);
    }
    public class ViewRenderService : IViewRenderService
    {
    private readonly IRazorViewEngine _razorViewEngine;
    private readonly ITempDataProvider _tempDataProvider;
    private readonly IServiceProvider _serviceProvider;

    public ViewRenderService(IRazorViewEngine razorViewEngine,ITempDataProvider tempDataProvider,IServiceProvider serviceProvider)
    {
        _razorViewEngine = razorViewEngine;
        _tempDataProvider = tempDataProvider;
        _serviceProvider = serviceProvider;
    }

    public async Task<string> RenderToStringAsync(string viewName, ViewDataDictionary viewData)
    {
        var httpContext = new DefaultHttpContext { RequestServices = _serviceProvider };
        var actionContext = new ActionContext(httpContext, new RouteData(), new ActionDescriptor());

        using (var sw = new StringWriter())
        {
            var viewResult = _razorViewEngine.FindView(actionContext, viewName, false);

            if (viewResult.View == null)
            {
                throw new ArgumentNullException($"{viewName} does not match any available view");
            }


            var viewContext = new ViewContext(
                actionContext,
                viewResult.View,
                viewData,
                new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
                sw,
                new HtmlHelperOptions()
            );

            await viewResult.View.RenderAsync(viewContext);
            return sw.ToString();
        }
    }

    }

Answer 1

Due to time constraints I abandoned the XUnit approach, wrote a test app and also utilised postman as this was an api requirement to render a pdf from a razor view.

Answer 2

I was getting the same error with core 2.0. The problem is RazorViewEngine is not working as expected with empty RouteData object;

So i injected IHttpContextAccessor and got HttpContext and RouteData from it;

Startup.cs:

  public void ConfigureServices(IServiceCollection services)
    {
        services.AddScoped<IViewRenderService, ViewRenderService>();
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        services.AddMvc();
    }

RazorToStringHelper.cs:

  public interface IViewRenderService
{
    Task<string> RenderToStringAsync(string viewName, object model);
}

public class ViewRenderService : IViewRenderService
{
    private readonly IRazorViewEngine _razorViewEngine;
    private readonly ITempDataProvider _tempDataProvider;
    private readonly IHttpContextAccessor _httpContextAccessor;

    public ViewRenderService(
        IRazorViewEngine razorViewEngine,
        IHttpContextAccessor httpContextAccessor,
        ITempDataProvider tempDataProvider)
    {
        _razorViewEngine = razorViewEngine;
        _tempDataProvider = tempDataProvider;
        _httpContextAccessor = httpContextAccessor;
    }

    public async Task<string> RenderToStringAsync(string viewName, object model)
    {
        var httpContext = _httpContextAccessor.HttpContext;

        var actionContext = new ActionContext(httpContext, httpContext.GetRouteData(), new ActionDescriptor());

        var viewResult = _razorViewEngine.FindView(actionContext, viewName, false);

        if (viewResult.View == null)
        {
            throw new ArgumentNullException($"{viewName} does not match any available view");
        }

        using (var sw = new StringWriter())
        {
            var viewDictionary = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary())
            {
                Model = model
            };

            var viewContext = new ViewContext(
                actionContext,
                viewResult.View,
                viewDictionary,
                new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
                sw,
                new HtmlHelperOptions()
            );

            await viewResult.View.RenderAsync(viewContext);
            return sw.ToString();
        }
    }

}