Add viewport method for Yahoo

lib/geocoder/results/yahoo.rb

@@ -35,6 +35,11 @@ module Geocoder::Result
       @data['hash']
     end
 
+    def viewport
+      boundingbox = @data['boundingbox'] || fail
+      %w(south west north east).map{ |i| boundingbox[i].to_f }
+    end
+
     def self.response_attributes
       %w[quality offsetlat offsetlon radius boundingbox name
         line1 line2 line3 line4 cross house street xstreet unittype unit

test/unit/lookups/yahoo_test.rb

@@ -24,6 +24,12 @@ class YahooTest < GeocoderTestCase
     assert_equal "Madison Square Garden, New York, NY 10001, United States", result.address
   end
 
+  def test_result_viewport
+    result = Geocoder.search("Madison Square Garden, New York, NY").first
+    assert_equal [40.749931, -73.994591, 40.750832, -73.993393],
+      result.viewport
+  end
+
   def test_raises_exception_when_over_query_limit
     Geocoder.configure(:always_raise => [Geocoder::OverQueryLimitError])
     l = Geocoder::Lookup.get(:yahoo)