testing a custom actionresult in mvc 2

Question

i have an actionresult that overrides Execute (as you do) and the actionresult basically receives a model, serializes it, and writes it out to the reponse via response.write(model as text).

ive done some looking around and i cant see an easy way to test the response is correct. i think the best way is to test instantiate the custom actionresult & model, call the execute method, and then somehome inspect the controllercontexts' response. Only problem is, how do i get the reponses output as a string? i read somewhere that you cant get the responses outputstream as text? if so, how do i verify that my content is being written to the response stream? i can test my serialiser to reduce the risk, but id like to get some coverage over the ExecuteResult override...

public class CustomResult: ActionResult
    {

        private readonly object _contentModel;
        private readonly ContentType _defaultContentType;

        public CustomResult(object contentModel, ContentType defaultContentType)
        {
            _contentModel = contentModel;
            _defaultContentType = defaultContentType;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            context.HttpContext.Response.Write(serialized model);
        }

    } 

Answer 1

You can get the output as text, but you do have to do a bit of extra work to make it all testable.

You'll need MVCContrib.TestHelper to get mocks set up for all the MVC components. On top of that I have a bit of code setting up access to the relevant parts of the request:

public class CustomTestControllerBuilder : TestControllerBuilder
{

    public CustomTestControllerBuilder()
    {
        var httpContext = new Moq.Mock<HttpContextBase>();
        var request = new Moq.Mock<HttpRequestBase>();
        var response = new Moq.Mock<HttpResponseBase>();
        var server = new Moq.Mock<HttpServerUtilityBase>();
        var _cache = HttpRuntime.Cache;

        httpContext.Setup(x=> x.Request).Returns(request.Object);
        httpContext.Setup(x => x.Response).Returns(response.Object);
        httpContext.Setup(x => x.Session).Returns(Session);
        httpContext.Setup(x => x.Server).Returns(server.Object);
        httpContext.Setup(x => x.Cache).Returns(_cache);


        var items = new Dictionary<object, object>();
        httpContext.Setup(x => x.Items).Returns(items);


        QueryString = new NameValueCollection();
        request.Setup(x => x.QueryString).Returns(QueryString);

        Form = new NameValueCollection();
        request.Setup(x => x.Form).Returns(Form);

        request.Setup(x => x.AcceptTypes).Returns((Func<string[]>)(() => AcceptTypes));

        var files = new WriteableHttpFileCollection();
        Files = files;
        request.Setup(x => x.Files).Returns(files);

        Func<NameValueCollection> paramsFunc = () => new NameValueCollection { QueryString, Form };
        request.Setup(x => x.Params).Returns(paramsFunc);

        request.Setup(x => x.AppRelativeCurrentExecutionFilePath).Returns(
                (Func<string>)(() => AppRelativeCurrentExecutionFilePath));
        request.Setup(x => x.ApplicationPath).Returns((Func<string>)(() => ApplicationPath));
        request.Setup(x => x.PathInfo).Returns((Func<string>)(() => PathInfo));
        request.Setup(x => x.RawUrl).Returns((Func<string>)(() => RawUrl));
        response.SetupProperty(x => x.Status);
        httpContext.SetupProperty(x=>x.User);

        var ms = new MemoryStream(65536);
        var sw = new StreamWriter(ms);
        response.SetupGet(x=>x.Output).Returns(sw);
        response.SetupGet(x => x.OutputStream).Returns(ms);

        response.Setup(x => x.Write(It.IsAny<string>())).Callback((string s) => { sw.Write(s); });
        response.Setup(x => x.Write(It.IsAny<char>())).Callback((char s) => { sw.Write(s); });
        response.Setup(x => x.Write(It.IsAny<object>())).Callback((object s) => { sw.Write(s); });

        //_mocks.Replay(HttpContext);
        //_mocks.Replay(request);
        //_mocks.Replay(response);

        TempDataDictionary = new TempDataDictionary();


        HttpContext = httpContext.Object;
    }

}
}

Note that OutputStream is now a MemoryStream rather than an actual web connection. With that set up you just need a few more lines to get the output that would be sent to the client:

 Result.ExecuteResult(c.ControllerContext);
 var ms = (MemoryStream)c.HttpContext.Response.OutputStream;
 c.HttpContext.Response.Output.Flush();
 ResultHtml = new UTF8Encoding().GetString(ms.GetBuffer());