Posted by Peter Donald Wed, 13 Jun 2007 14:01:00 GMT

It can be useful at times to unit test helpers to make sure they generate correct html. It is not obvious how to do this at first. So far I have been testing my helper by defining a class “MyClass” at the top of my unit test and including all the appropriate modules. I also need to define a url_for method if I ever want to test helpers that generate links.

The code follows (Replace MyHelper with your appropriate helper class);

class MyClass
  include ERB::Util
  include ActionView::Helpers::TagHelper
  include ActionView::Helpers::UrlHelper
  include MyHelper

  def url_for(options)
    ActionController::Routing::Routes.reload if ActionController::Routing::Routes.empty?
    generated_path, extra_keys = ActionController::Routing::Routes.generate_extras(options, {})
    generated_path
  end
end

Then in my tests I do something like;

def test_revision_link
  assert_equal(
    "<a href=\"http://svn.sourceforge.net/viewvc/jikesrvm?view=rev&amp;revision=22\">22</a>", 
    MyClass.new.revision_link(22))
end

Seems easy enough to do in retrospect but things usually do.