Re: Test driving a real world data parser

Phlip <[email protected]> Thu, 16 Nov 2006 11:27:58 -0800
Newsgroups gmane.comp.programming.test-driven-development,gmane.comp.programming.test-first-user-interfaces
Message-ID <[email protected]>
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Tim Ottinger wrote:

>  Personally I like the advice to clean it up with tidy.  Tidy is awesome.

Then, XPath is a sledge-hammer to TDD raw HTML.

(Note - sometimes you just write the HTML, and sometimes you TDD at
another level. When you TDD at the HTML surface itself, use XPath.)

Here's a sample of my current project:

    @xdoc = Document.new(updater.body)
    assert_xpath "/span/input[@name = 'frob[id]' and @value = '#{frob.id}']"

    assert_xpath "/span/script[@type = 'text/javascript']" do |node|
      assert_equal "Form.Element.disable('frob_zone_mode_1');", node.text()
    end

The first xpath asserts that we generated a span containing a (hidden)
input field with the given value.

The second xpath asserts this span also contains a script. Then a
nested assertion checks the script contains the right JavaScript.

My assert_xpath can nest calls to more assert_xpath, and they will
work on the selected node. So I could, for example, start at a form,
then drill down and inspect fields in the form.

The general principle here is one can TDD a scripting language by
driving a parser which reads that scripting language. And so this
leads to the ideal that we should only select scripts for which
parsers are available!

-- 
  Phlip
  http://c2.com/cgi/wiki?ZeekLand  <-- NOT a blog!!

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            <p>Tim Ottinger wrote:<br>
<br>
&gt;  Personally I like the advice to clean it up with tidy.  Tidy is awesome.<br>
<br>
Then, XPath is a sledge-hammer to TDD raw HTML.<br>
<br>
(Note - sometimes you just write the HTML, and sometimes you TDD at<br>
another level. When you TDD at the HTML surface itself, use XPath.)<br>
<br>
Here's a sample of my current project:<br>
<br>
@xdoc = Document.new(<wbr>updater.body)<br>
    assert_xpath &quot;/span/input[<wbr>@name = 'frob[id]' and @value = '#{frob.id}'<wbr>]&quot;<br>
<br>
assert_xpath &quot;/span/script[<wbr>@type = 'text/javascript'<wbr>]&quot; do |node|<br>
      assert_equal &quot;Form.Element.<wbr>disable('<wbr>frob_zone_<wbr>mode_1');<wbr>&quot;, node.text()<br>
    end<br>
<br>
The first xpath asserts that we generated a span containing a (hidden)<br>
input field with the given value.<br>
<br>
The second xpath asserts this span also contains a script. Then a<br>
nested assertion checks the script contains the right JavaScript.<br>
<br>
My assert_xpath can nest calls to more assert_xpath, and they will<br>
work on the selected node. So I could, for example, start at a form,<br>
then drill down and inspect fields in the form.<br>
<br>
The general principle here is one can TDD a scripting language by<br>
driving a parser which reads that scripting language. And so this<br>
leads to the ideal that we should only select scripts for which<br>
parsers are available!<br>
<br>
-- <br>
  Phlip<br>
  <a href="http://c2.com/cgi/wiki?ZeekLand">http://c2.com/<wbr>cgi/wiki?<wbr>ZeekLand</a>  &lt;-- NOT a blog!!<br>
</p>
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