I'm a Floridian web engineer who planted his roots in Paris. Some of my favorite past-times are analyzing and optimizing development processes, building solid APIs, mentoring junior devs, and long walks on the beach.

Test a will_paginate Custom Renderer 01-22-2012

I was recently working on a project where my employer wanted me to make the site's current pagination work the way the old site's pagination worked. I had recently switched over using will_paginate, and while there are a number of good resources for making customized link renderers: frivolous, thewebfellas are a few. They don't really mention testing.

While searching through the internets, I eventually stumbled upon this on tsigo's github with some specs for his renderers. For me, I just had to test an override of windowedpagenumbers, and link. Setting up the test can be seen easily enough from the github file, but essentially, you just create an instance of WillPaginate::Collection and pass that into whatever renderer you have created along with any options like so:


@renderer = LinkRenderer.new
@renderer.stubs(:url).returns('')
@collection = WillPaginate::Collection.new(page, per_page, total_entries)
@renderer.prepare(@collection, options, '')

@renderer.method_name.should do_something

You will have noticed that I've stubbed out the url method. That is because we aren't using a real collection of objects and therefore there is no url to generate.

Testing File operations 03-24-2011

I've recently been working on a gem that will integrate git and pivotal into my current command-line workflow. I'll talk more about that in a future post, but check it out if you're interested. As I've been working on it, I have become increasingly aware how awesome mocking and stubbing are. I've been using mocha(gem install mocha #bros) for all of my needs and after a little playing around it has made me a very happy person. I haven't had much use for either until this gem I've been working on. The gem does more file operations that I normally do since most web stuff is heavier on the db action.

On this project I ran into an issue where I wasn't sure how to test the following code.


def load_project_id
  File.open('.git/config') do |file| 
    file.each_line do |line| 
      if line.slice('[pivotal]')
        return file.gets.tr("\s\t\n",'').split(' = ').last
      end
    end
  end
end

For this chunk of code, I wanted to spoof the variable 'file' so that I could make sure that everything in the File.open block does what it needs to. At first I thought that there might be a way to stub the variable that comes in to the block, but it ends up there is a more straight forward thing to do. I ended up turning File.open(".git/config") into File.open(git_config) where git_config is a method that determines the git config directory based on the current working directory. This way I can test this method by stubbing the git_config method with some file I've put in the /tmp directory and keep my config files clean.