Wolfmans Howlings

Using RSpec to test HAML helpers

Posted by Jim Morris Sat, 14 Jul 2007 23:40:00 GMT

UPDATED for HAML 2.0 and RSpec 1.1.5 - Changed open to haml_tag, prefix helper. to all rspec calls...

The most recent release of HAML introduced a neat feature that allows you to use HAML-like syntax in your helpers to generate HTML HAML#haml_tag.

A question on the HAML news group asked how to test a helper that uses HAML#haml_tag (used to be open/puts) and thanks to Nathan on that list I finally got RSpec to do it. As shown below.

However a really good point was made that really in RSpec the way to test anything is to use mocks to mock any call to an outside method thus focusing the test on the specific module under test. Generally I agree with that philosophy. But this is way cool so I thought I'd do it anyway, and also as it is a new feature in HAML one may not want to simply trust HAML to generate the correct HTML.

So in my application_helper.rb I have a simple helper...

module ApplicationHelper

 ...

  def display_flash
    for name in [:notice, :warning, :error]
      if flash[name]
        haml_tag :div, flash[name], {:class => name.to_s}
      end
    end
    nil
  end

  ...

end

This is called in my views as...

- display_flash

Notice the - instead of =, this is because the open (and puts) write output directly to the HAML buffer, and so this routine should return nothing. (This is also a very simply case and does not show off the utility of the open/puts methods, I'll show one of those later on).

The RSpec helper test that tests this is as follows...

# File: spec/helpers/application_helper_spec.rb
require File.dirname(__FILE__) + '/../spec_helper'

describe ApplicationHelper do

  before :each do
    helper.extend Haml
    helper.extend Haml::Helpers 
    helper.send :init_haml_helpers
  end

  it "should display flash" do
    for name in [:notice, :warning, :error]
      flash[name]= "flash #{name.to_s} message"
      helper.capture_haml{
        helper.display_flash
      }.should =~ /<div class='#{name.to_s}'>\s*#{flash[name]}\s*<\/div>/
      flash[name]= nil
    end
  end

end

Excellent, a simple test for the HTML generated by my haml helper. NOTE the setup required in the before :each, this sets up the haml helpers in the helpers context

Why would I want to use HAML#open you ask?

Well it makes the helpers look so much tidier IMHO, take this example from my previous post on tag clouds, the re-factored helper now looks like this...

  # display a tag cloud for the given model
  def tag_cloud(model, title= nil)
    m= model.to_s.camelcase.constantize
    plural= model.to_s.capitalize.pluralize
    title ||= plural
    tags= m.tag_counts(:order => 'tags.name')
    return false if tags.empty?
    urlmeth= "tagged_#{model.to_s.pluralize}_path".to_sym
    haml_tag :div, {:class => "tagcloud"} do
      haml_tag :h3, title
      tags.each do |t|
        next if t.name == 'FAQ'
        haml_tag :span, {:style => "font-size:#{calc_size(t.count)}%"} do
          puts link_to(h(t.name), self.send(urlmeth, :tag => t.name))
        end
      end
    end
    return true
  end      

So much cleaner, plus I can return a boolean to indicate if there was anything output or not, which tells me if I need to output an <hr/> or not.

Posted in RSpec, Rails, HAML | Tags haml, helpers, rspec, test | 8 comments | no trackbacks