How to start write test for gems?

[regedarek]

Hi,
I have some experience with testing Rails application using Rspec.

But now i tried to write tests for simple gem: https://github.com/regedarek/soup-client
I know it will not be easy, but i want to learn this. Could you give me some tips or send some links how to started  or example of good simple tests in gems because this is i think much more difficult then testing web applications.

What should i test first?
In first spec i think I should check Agent class?
 

# agent_spec.rb
require File.expand_path(File.dirname(__FILE__) + '/spec_helper')

describe "Soup Client" do
  before do
    @agent = Soup::Agent.new
  end
  it "should connect to soup" do
    @agent.host.should == "http://soup.io"
  end
end

But this spec of course fails.

        @@ -1,2 +1,19 @@
       -"http://soup.io"
       +#<Soup::Agent:0xa87f8ac
       + @agent=
       +  #<Faraday::Connection:0xa87f834
       +   @builder=
       +    #<Faraday::Builder:0xa87f58c
       +     @handlers=
       +      [Faraday::Request::UrlEncoded,
       +       Faraday::Response::Logger,
       +       Faraday::Adapter::NetHttp]>,
       +   @headers={},
       +   @host="www.soup.io",
       +   @options={},
       +   @parallel_manager=nil,
       +   @params={},
       +   @path_prefix="/",
       +   @port=nil,
       +   @scheme="https",
       +   @ssl={}>>
     # ./spec/soup_spec.rb:8:in `block (2 levels) in <top (required)>'

I would like to learn how to get access to this variables like @host @builder and how to test each one. Any tips?

Thanks in advance