JSON Helper for API specs

messages_spec.rb

# spec/requests/api/v1/messages_spec.rb
describe "Messages API", type: :request do
  it 'retrieves a specific message' do
    message = FactoryGirl.create(:message)    
    get "/api/v1/messages/#{message.id}"

    # test for the 200 status-code
    expect(response).to be_success

    # check that the message attributes are the same.
    expect(json['content']).to eq(message.content) 

    # ensure that private attributes aren't serialized
    expect(json['private_attr']).to eq(nil)
  end
end

request_helpers.rb

# spec/support/request_helpers.rb
module Requests
  module JsonHelpers
    def json
      @json ||= JSON.parse(response.body)
    end
  end
end

spec_helper.rb

RSpec.configure do |config|

  config.include Requests::JsonHelpers, type: :request

end

Read more: http://matthewlehner.net/rails-api-testing-guidelines/