DisplayFormat unit testing with HtmlHelper

MyModel _model = new MyModel() { PriceDate = new DateTime(2000, 1, 1)};

var helper = new System.Web.Mvc.HtmlHelper<MyModel>(new ViewContext(), new ViewPage());
var result = helper.DisplayFor(m => _model.PriceDate);

Assert.That(result, Is.EqualTo(expected));

I want to test that the output produced by calling DisplayFor is in the format specif开发者_StackOverflow社区ied by...

[DisplayFormat(DataFormatString = "{0:dd/MM/yy}")]
public DateTime? PriceDate { get; set; }

The code compiles but fails with a NullReferenceException at DisplayFor.

Can anyone help me make this work?

(Note: This is a trivial example of a larger problem)

The steps are quite long so I couldn't write here. I wrote about it at my blog :D

http://thoai-nguyen.blogspot.com/2011/07/unit-test-displayformat-attribute.html

Cheers

I use the following code to test and validate html helpers.

Validation is a another example.

Try the following:

    var sb = new StringBuilder();
    var context = new ViewContext();
    context.ViewData = new ViewDataDictionary(_testModel);
    context.Writer = new StringWriter(sb);
    var page = new ViewPage<TestModel>();
    var helper = new HtmlHelper<TestModel>(context, page);

    //Do your stuff here to exercise your helper

    //Following example contains two helpers that are being tested
    //A MyCustomBeginForm Helper and a OtherCoolHelperIMade Helper
    using(helper.MyCustomBeginForm("secretSauce"))
    {
       helper.ViewContext.Writer.WriteLine(helper.OtherCoolHelperIMade("bigMacSauce"));
    }
    //End Example

    //Get the results of all helpers
    var result = sb.ToString();

    //Asserts and string tests here for emitted HTML
    Assert.IsNotNullOrEmpty(result);