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Test Your Rabl's View

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Since several month, I use only Rabl to do all my API. To me this gems is really awesome. Before using it, I try doing all of my API with the #to_json method. But it was a nightmare. If you already try to do that, you understand what I mean. The most bad case is when you want represent your object in different way depending of where is represent.

Rabl simply clean

To manage your JSON and XML view, the most common gem is JBuilder and XmlBuilder, both are created by DHH. To me it’s not a good DSL and can be a little too verbose. Rabl has a clean a simplest DSL and you just need one view to generate XML and JSON. You can even generate some other output with Rabl.

A little example of Rabl’s view :

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object @post
attribute :content
child(:author) do
  attribute :firstname, :lastname
end

Test your Rabl’s view

To test the output of this view, you have multiple choice. You can generate this view in an integration test and test this output. You can do it in your controller test. Or the best, test only your output on your view test. With this last choice, you can define what you really put on your view and test only your rabl representation. In this case you can have a flexible and fast test.

Since Rabl 0.6.0, a new method help to generate your view directly. It’s with this method you can simply test our view.

An example of how we can test our view ( spec/views/posts/show_rabl_spec.rb) :

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require 'spec_helper'

describe "blogs/show.rabl" do

    let(:auhor) { Author.new(:firstname => 'Cyril', :lastname => 'Mougel') }
    let(:blog) { Blog.new(:content => 'hello', :author => author) }
    let(:valid_json) {
      {
        :content => blog.content,
        :author => {
          :firstname => author.firstname,
          :lastname => author.lastname
        }
      }.to_json
    }

    let(:render) {
      Rabl.render(
        blog,
        'blog/show',
        :view_path => 'app/views'
      )
    }

    it 'should render valid_json' do
      render.should eql(valid_json)
    end

end

We have a really simple test unit with a complet JSON validation. This test is fast because no need doing some database request and no controller stuff needed.

But, I found a little limitation in this method. You can’t pass some locals variables. So you can only test this render with value pass on the first params. If you have some other object you want use, you can’t. I start a Pull Request to pass this variables in a :locals options. You can follow it on github

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