Created paged result class, with passing feature and specs

TODO

@@ -1,7 +1,6 @@
 @milestone Basic artist methods +done
 @milestone Improve API, documentation and implement missing features
-  @iteration Fluent Api
-    Separate out the ugly xml mapping classes and provide a nice fluent interface based on an Artist object eg. anArtist.familiarity should return the familiarity as a number (transparently calling the webservice if required)
+  @iteration Fluent Api +done
   @iteration Paging
     Create a nice interface for paged results (urls, videos, blogs, audio etc).
   @iteration Docs

features/fluent/artist_audio.feature

@@ -4,8 +4,10 @@ Feature: Artist audio
 
   Scenario: Artist audio
     When I retrieve the audio for "music://id.echonest.com/~/AR/ARVVZQP11E2835DBCB"
-    Then I should get some results
+    Then I should get some paged results
     And a result should have a url
     And a result should have a link
     And a result should have a release
     And a result should have a title
+    And a later result should have a url
+

features/fluent/step_definitions/fluent_steps.rb

@@ -16,6 +16,20 @@
    @result.length.should_not == 0
 end
 
+Then /^I should get some paged results$/ do
+   @result.should_not be_nil
+   @result.should be_kind_of(PagedResult)
+   @result.length.should_not == 0
+   @result.found.should_not == 0
+end
+
+Then /^a later result should have a ([^ ]*)$/ do |prop|
+   @later_result ||=  @result[@result.length+1]
+   @later_result.send(prop.to_sym).should_not be_nil
+end
+
+
+
 Then /^I should get a numeric result$/ do
    @result.should_not be_nil
    @result.should be_kind_of(Numeric)

lib/echonest.rb

@@ -2,6 +2,7 @@
 require 'happymapper'
 require 'open-uri'
 require 'activesupport'
+require 'delegate'
 
 module EchoNest
    def self.api_key=(api_key)
@@ -15,6 +16,8 @@ def self.api_key
 end
 
 require "echonest/api_request.rb"
+require "echonest/paged_result.rb"
+
 require "echonest/artist.rb"
 require "echonest/xml/artist_doc.rb"
 

lib/echonest/artist.rb

@@ -18,7 +18,11 @@ def self.service(name, options = {})
         define_method name do
           return instance_variable_get("@#{name.to_s}") if instance_variable_get("@#{name.to_s}")
           result = self.send("get_#{name.to_s}")
-          instance_variable_set("@#{name.to_s}", result.results.docs)
+          pager = Proc.new { |start, rows| 
+            self.send("get_#{name.to_s}", :start => start, :rows => rows).results
+          }
+          page = PagedResult.new result.results, pager 
+          instance_variable_set("@#{name.to_s}",  page)
         end
       else
         if !options[:provides]

lib/echonest/paged_result.rb

@@ -0,0 +1,32 @@
+
+
+
+module EchoNest
+  class PagedResult < DelegateClass(Array)
+
+    def initialize(results, block)
+      @results = results
+      @update = block
+      @available = @results.docs
+      super(@available)
+    end
+
+    def found
+      @results.found
+    end
+
+    def next_page
+      results = @update.call @available.length, 15
+      @available += results.docs
+      self.__setobj__(@available)
+    end
+
+    def [](i)
+      return @available[i] if @available[i]
+      next_page
+      @available[i]
+    end    
+
+
+  end
+end

spec/echonest/paged_result_spec.rb

@@ -0,0 +1,66 @@
+require File.dirname(__FILE__) + "/../spec_helper.rb"
+
+include EchoNest
+
+describe "PagedResult" do
+  before :each do
+    @docs = mock("docs", :length => 2)
+    @results = mock("results", :docs => @docs)
+    @block_body = mock("block body")
+    @block = Proc.new { |*args| @block_body.called(*args) }
+    @page = PagedResult.new @results, &@block
+
+    @docs2 = mock("docs2", :length => 2)
+    @page2 = mock("page2", :docs => @docs2)
+    @block_body.stub!(:called).and_return(@page2)
+
+  end
+
+  describe "each" do
+    it "should iterate over items in results" do
+      @docs.should_receive(:each)
+      @page.each 
+    end
+  end
+
+  describe "[]" do
+    it "should return the nth doc" do
+      @docs.should_receive('[]').twice().with(1).and_return(:doc)
+      @page[1].should == :doc
+    end  
+
+    it "should get the next page if index is out of range" do
+      @docs.should_receive('[]').at_least(1).and_return(nil)
+      @page.should_receive(:next_page)
+      @page[2]
+    end
+
+  end
+
+  describe "next_page" do
+
+    before(:each) do
+      @merged_docs = mock("Merged Docs", :length => 4)
+      @docs.stub!('+').and_return(@merged_docs)
+    end
+
+    it "should fetch the next page" do
+      @block_body.should_receive(:called).with(2, 15).and_return(@page2)
+      @page.next_page 
+    end  
+
+    it "should update the delegate" do
+      @docs.should_receive('+').with(@docs2).and_return(@merged_docs)
+      @page.next_page 
+      @page.length.should == 4
+    end
+
+
+  end
+
+  describe "length" do
+
+  end
+
+
+end