Test Driven Ajax (on Rails)

assert_params

When the test fails, upgrade the source to pass in those data:

  def decode(ypath)
    ypath =~ /^node(:.*)/
    return $1.gsub(':', '//')
  end
...

        href = {
          :id => 'link_'+ypath,
          :url => {
            :action    => 'display_iframe',
            :page_name => page_name,
            :ypath     => decode(ypath)
            } }
        @x << @page.link_to_remote($1, href)

That triggers an error message, which tells us how to upgrade the test:

        assert_xpath 'Statement[1]//ArgumentList[1]' do |node|
          assert_equal
'/wiki/display_iframe?ypath=%2F%2Ftest_uncle_wiggily&page_name=WikiTestPage',
                       assert_argument(1)
        end

The front-slashes were predictably escaped as %2F, and the arguments arrived in a different order.

Patching that test case isn't good enough. For every feature in our code, including the systems that generate a URI's path and query segments, we need a matching feature on the test side:

  def assert_params(path_query)
    path, query = path_query.split('?')
    params = {}

    if query
      query.split('&').each do |item|
        key, value = item.split('=')
        params[key.to_sym] = CGI::unescape(value)
      end
    end

    return [path, params]
  end

  def test_test_nodes_link_to_display_iframe
    render_wiki(get_omap)

    assert_xpath '//strong/a[ . = "test" ]' do |a|
      assert_equal '#', a.href
      assert_js 'ajax = ' + a.onclick do
        assert_xpath 'Statement[1]//ArgumentList[1]' do
          command, params = assert_params(assert_argument(1))
          assert_equal '/wiki/display_iframe', command
          assert_equal '//test_uncle_wiggily', params[:ypath]
          assert_equal 'WikiTestPage', params[:page_name]
        end
      end
    end
  end

And that ...