Wolfmans Howlings

A programmers Blog about Programming solutions and a few other issues

Using RSpec to test HAML helpers

Posted by Jim Morris on Sat Jul 14 16:44:33 -0700 2007

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...

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...

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...

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 HAML,Rails,RSpec  |  Tags test,haml,rspec,helpers  |  9 comments


  1. Evgeny said on Sun Jul 15 13:00:25 -0700 2007
    I guess the file you will put that in will be spec/helpers/application_spec.rb
    Because you, and http://rspec.rubyforge.org/documentation/rails/writing/helpers.html don't specify the file naming. I took a guess, and it seems to be okey ...

    Thanks for the helper, and the spec for the helper! :)

    Do you know of any repository of small+usefull helpers that one would usually put in application helpers? That kind of helpers that you take with you to each new application you write ....

    Like for example (that I have in my apps):

        def whitespace(times = 1)
          " " * times

  2. wolfmanjm said on Sun Jul 15 13:25:28 -0700 2007
    Yes that is where I put it.

    I'm not aware of a place for those helpers, but if you find one let me know :)
  3. Evgeny said on Thu Jul 19 15:58:11 -0700 2007
      it "should display flash" do
        for name in [ :notice, :warning, :error ]
          flash[name]= "flash #{name.to_s} message"
          capture_haml {
          }.should have_tag "div.#{name.to_s}", 1, :text => flash[name]
  4. Evgeny said on Thu Jul 19 15:59:10 -0700 2007
    Ohh... I actually just used :
      before(:each) do
        @haml_is_haml = true
        @haml_stack = [Haml::Buffer.new(:attr_wrapper => "'")]
    because I have more haml helpers to test than just one.
  5. wolfmanjm said on Thu Jul 19 16:05:40 -0700 2007
    Thanks I wasn't sure that ` have_tag` would work, but its good to know thats an option.
  6. Evgeny said on Sun Jul 22 05:50:21 -0700 2007
    Is there a way to add those
      include ActionView::Helpers
      include Haml::Helpers

    into spec_helper.rb ?
    and perhaps even the `@haml_is_haml` and `@haml_stack` ....

    It's kind of annoying adding those to each description I have of helpers. Not DRY at all. Especially for a non-rails project I am working on.
  7. Evgeny said on Sun Jul 22 08:42:30 -0700 2007
    One can also use automatic inclusion for haml helpers for all helper tests<br/>
    by editing `spec/spec_helper.rb`, like so:

        Spec::Runner.configure do |config|
          config.include Haml::Helpers
          config.include ActionView::Helpers

          config.before(:each, :behaviour_type => :helper) do
            @haml_is_haml = true
            @haml_stack = [Haml::Buffer.new(:attr_wrapper => "'")]

    Or if using Haml trunk, then you can also do it like so:

        Spec::Runner.configure do |config|
          config.before(:each, :behaviour_type => :helper) do

    Though I didn't test this enough, and it could be a bit wrong ... especially regarding the trunk method.
  8. meekish said on Sun Aug 19 11:12:26 -0700 2007
    That's very nice. I learn something new every day.
  9. Len Wholey said on Thu Sep 19 10:17:17 -0700 2013
    Thank you!

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