Test output from HtmlTextWriter

Question

Quite simply I want to be able to test that a Asp.Net web forms server control is outputting the correct Html as it will be building dynamic content. I'm just starting to create the control and wanted to do it in a TDD style building up the Html that gets output.

I've created a separate class to do the actual Html building so that I am able to test it in isolation outside of the normal Asp.Net pipeline.

In my unit tests I can control what html is returned but I'm having problems confirming that the html contains the markup I am expecting for example:

<div id="wrapper">
    <div id="fields">
    </div>
    <div id="main">       
    </div> 
</div>

and as I'm using Nunit I would like to be able to store the output from the server control and test it by using Is.StringMatching like:

Assert.That(output, Is.StringMatching("<div id=\"main\">.*?</div>"));

This unfortunately won't work because of the extra \r \n \t instructions that the HtmlTextwriter outputs.

The way I'm currently using it is by creating a StringWriter and then using it to create the HtmlTextWriter like this:

    stringWriter = new StringWriter();
    htmlTextWriter = new HtmlTextWriter(stringWriter);

and I then call the following method:

public string Build(HtmlTextWriter writer)
{

    writer.AddAttribute(HtmlTextWriterAttribute.Id, "wrapper");
    writer.RenderBeginTag(HtmlTextWriterTag.Div);

    writer.AddAttribute(HtmlTextWriterAttribute.Id, "fields");
    writer.RenderBeginTag(HtmlTextWriterTag.Div);
    writer.RenderEndTag();
    writer.WriteLine();
    writer.AddAttribute(HtmlTextWriterAttribute.Id, "main");
    writer.RenderBeginTag(HtmlTextWriterTag.Div);
    writer.RenderEndTag();
    writer.RenderEndTag();



    return writer.InnerWriter.ToString();
}

As the Html gets more complex I can forsee additional problems verifying that the output is correct.

An additional constraint is the requirement to be able to run the tests via a CI server (most likely TeamCity) so all code or referenced libraries need to sit in my solution.

I've done a fair bit of googling but cannot seem to find much about how to test the Html output can anybody offer any suggestions for the best way forward?

score 2 · Accepted Answer · answered Mar 01 '11 at 15:40

2

You could make sure that your html output is well-formed xml. Then, in your testing code, load the output into an XmlDocument, thus you're free of all whitespace issues. You can then check that all the tags are really there, and are where they are supposed to be with the XmlDocument.

answered Mar 01 '11 at 15:40

Sébastien Nussbaumer

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Thanks for that, not thought of loading into XmlDocument, may work – Nathan Mar 01 '11 at 16:06
This will also automatically enforce the well-formedness of your code, although this may be of minor importance here. – Sébastien Nussbaumer Mar 01 '11 at 16:14
Sorry its taken a while been busy but gone with your answer as it best suits my current situation. Cheers – Nathan Mar 21 '11 at 10:17

score 0 · Answer 2 · answered Mar 01 '11 at 15:53

0

I'd load it into HtmlAgilityPack and then either query that using XPath or use the fizzler project to do some QuerySelectorAll() jQuery style.

answered Mar 01 '11 at 15:53

dezfowler

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Will I have any issues with CI server in raltion to that? – Nathan Mar 01 '11 at 16:06
Don't see why - it doesn't start up browsers or anything like that. – dezfowler Mar 02 '11 at 18:55

score 0 · Answer 3 · answered Mar 02 '11 at 11:32

0

The Gallio/MbUnit's built-in ability to test XML and HTML could help you.

answered Mar 02 '11 at 11:32

Yann Trevin

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Thanks for that, I'll have a look at it – Nathan Mar 02 '11 at 13:25

Test output from HtmlTextWriter

3 Answers3