Interesting Things

• In exploring options for RSpec testing of XML responses, one project decided
  a custom XPath matcher
  would do the trick nicely:

  items = Item.find(:all)
  get :index
  
  
  response.body.should     have_nodes("//items/item", items.size)
  response.body.should     have_xpath("//items/item[ position() = 1 and @id = '0001' ]")
  response.body.should_not have_xpath("//bogus")
  

  Some other possibilities:

  • Hashes…

    items = Item.find(:all)
    get :index
    
    
    hash = Hash.from_xml(response.body)
    hash['ancestor']['parent']['items']['item'].size.should == items.size
    hash['ancestor']['parent']['items']['item'][0]['id'].should == '0001'
    hash['ancestor']['parent']['bogus'].should be_nil
    

  • Hpricot…

    items = Item.find(:all)
    get :index
    
    
    doc = Hpricot(response.body)
    doc.search("//items/item").size.should == items.size
    doc.at("//items/item[ @id = '0001' ]").position.should == 1
    doc.at("//bogus").should be_nil
    

  • assert_select from Rail’s Test::Unit (using CSS-style selectors)…

    items = Item.find(:all)
    get :index
    
    
    assert_select("items > item", :count => 5)
    assert_select("items > item:nth-child(1)[id=?]", '0001')
    assert_select("bogus", false)
    

  What are your favorite techniques for asserting XML/XPath?

• Something to consider when test-driving controller code:

  You’re working with ActionController::TestResponse. So, response.success?,
  response.redirect?, etc. are available for you there (since they are
  defined on TestResponse), but not in your actual controllers. That is,
  things blow up if you try to use @response.success? in your application,

  e.g. to determine whether or not to store the current URL and redirect there
  after a login.