Rails - Jul 2011 - functional testing unobtrusive JavaScript to update a portion of a page

I recently updated an application to Rails 3.0, and I ran into a testing
question while doing so.  I had one bit of a view that looked like this with
Rails 2.x:

 <% form_remote_tag :url => { :action => :answer, :item => ask },
:update =>
"answer" %>

where the corresponding controller method ended with:

    render :partial => ''answer'', :object => @item

In the Rails 3 version, :update isn''t available in form_tag, so the
controller method had the render line removed, and instead I added a file
answer.js.erb containing the following:

$(''answer'').update("<%= escape_javascript(render
:partial => ''answer'',
:object => @item) %>");

That works great (and I like the HTML that results, much more stylish than
the older version), but I can''t test it as well as I would have liked.
 Before, I could get at the HTML that was generated by that render :partial
line by using assert_select, as follows:

  def test_get_answer
    get :index
    post :answer, :item => @one.id

    assert_select "p.qa", "Answer 1"
  end

The problem with the new version is that the return value is now JavaScript,
which I can''t take apart via assert_select.  So, for now, I''m
doing this:

  def test_get_answer
    get :index
    post :answer, :format => ''js'', :item => @one.id

    assert(response.body.include? "Answer 1")
  end

which is certainly better than nothing, but isn''t nearly as precise as
I''d
like.

Any recommendations for a better way to test this sort of thing?

Thanks,
David Carlton
carlton-1jVtk91VtHFg9hUCZPvPmw@public.gmane.org

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On Wed, Jul 13, 2011 at 9:00 PM, David Carlton
<carlton-1jVtk91VtHFg9hUCZPvPmw@public.gmane.org> wrote:
>
> Any recommendations for a better way to test this sort of thing?
>
(Where "this sort of thing" is updating body elements via unobtrusive
JavaScript.)

In case anybody else is curious, here''s what I ended up with:

The source .js.erb file:

$(''answer'').update("<%= escape_javascript(render
:partial => ''answer'',
:object => @item) %>");

The source partial .html.erb file:

(something that includes <p
class="qa">text_that_I_want_to_assert_on</p>)

And the test:

  def unescape_javascript(escaped)
    escaped.gsub("\\''",
"''").gsub("\\\"",
"\"").gsub("\\n", "\n").
      gsub("\\\\", "\\").gsub("<\\/",
"</")
  end

  def assert_encoded_update(body, element_to_update)
    assert_not_nil(/\$\(''(.*)''\)\.update\("(.*)"\);/
=~ body)
    assert_equal(element_to_update, $1)
    yield(HTML::Document.new(unescape_javascript($2)).root)
  end

  def test_get_answer
    get :index
    post :answer, :format => ''js'', :item => @one.id

    assert_encoded_update(response.body, "answer") do |replacement|
      assert_select(replacement, "p.qa",
"text_that_I_want_to_assert_on")
    end
  end

Probably room for improvement (I certainly don''t claim that
unescape_javascript handles all the cases that escape_javascript handles),
but it works for my purposes.

-- 
David Carlton
carlton-1jVtk91VtHFg9hUCZPvPmw@public.gmane.org

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