Question

Here is my test:

[TestFixture]
public class DisplayingPageLinks
{
    [Test]
    public void Can_Generate_Links_To_Other_Pages()
    {
        //Arrange: We're going to extend the Html helper class.
        //It doesn't matter if the variable we use is null            
        HtmlHelper html = null;

        PagingInfo pagingInfo = new PagingInfo(){
            CurrentPage = 2,
            TotalItems = 28,
            ItemsPerPage = 10
        };

        Func<int, String> pageUrl = i => "Page" + 1;

        //Act: Here's how it should format the links.
        MvcHtmlString result = html.PageLinks(pagingInfo, pageUrl);

        //Assert:
        result.ToString().ShouldEqual(@"<a href=""Page1"">1</a><a href=""Page2"">2</a><a href=""Page3"">3</a>");
    }
}

Here is the PageLinks extension method:

public static MvcHtmlString PageLinks(this HtmlHelper html, PagingInfo pagingInfo, Func<int,string> pageUrl)
{
    StringBuilder result = new StringBuilder();

    for (int i = 1; i < pagingInfo.TotalPages; i++)
    {
        TagBuilder tag = new TagBuilder("a");
        tag.MergeAttribute("href", pageUrl(i));
        tag.InnerHtml = i.ToString();
        if (i == pagingInfo.CurrentPage)
        {
            tag.AddCssClass("selected");
        }
        result.Append(tag.ToString());
    }

    return MvcHtmlString.Create(result.ToString());
}

Finally here is the result for the running test:

SportsStore.UnitTests.DisplayingPageLinks.Can_Generate_Links_To_Other_Pages:
Expected string length 63 but was 59.
Strings differ at index 24.
Expected: “123” But was: “12”
———————————–^

The error doesn’t copy the way it’s shown in the GUI – sorry.

Can you give me some suggestions as to why NUnit is saying it receives something I don’t expect it to give out.

According to what I’m reading in the PageLinks extension method, it seems that the markup should be formed correctly.

Any suggestions? I’m a TDD newbie and really trying to learn here. 🙂

---

Edit:

It seems the culprit was this. My Test was using:
Func pageUrl = i => “Page” + 1;

instead of

Func pageUrl = i => “Page” + i;

But now there’s another error. 🙁

It seems something is wrong when calculating the amount of pages in the PagingInfo class:

public class PagingInfo
{
    public int TotalItems { get; set; }
    public int ItemsPerPage { get; set; }
    public int CurrentPage { get; set; }

    public int TotalPages
    {
        get { return (int)Math.Ceiling((decimal)TotalItems / ItemsPerPage); }
    }
}

It seems the error stems on the fact that this is returning 2 pages, instead of 3.

Is there something wrong in this calculation?

Answer 1

(Replying to the new question posed in your edit.) Your loop in PageLinks() is starting with i = 1 and having i < pagingInfo.TotalPages as condition – a classical off-by-one error. 🙂