Handle up to 4 redirects in http fetch code, tests for it

lib/fastimage.rb

@@ -143,7 +143,7 @@ class FastImage
     @property = options[:type_only] ? :type : :size
     @timeout = options[:timeout] || DefaultTimeout
     @uri = uri
-    
+
     if uri.respond_to?(:read)
       fetch_using_read(uri)
     else
@@ -172,9 +172,27 @@ class FastImage
   private
 
   def fetch_using_http
+    @redirect_count = 0
+
+    fetch_using_http_from_parsed_uri
+  end
+  
+  def fetch_using_http_from_parsed_uri
     setup_http
     @http.request_get(@parsed_uri.request_uri) do |res|
+      if res.is_a?(Net::HTTPRedirection) && @redirect_count < 4
+        @redirect_count += 1
+        begin
+          @parsed_uri = URI.parse(res['Location'])
+        rescue URI::InvalidURIError
+        else
+          fetch_using_http_from_parsed_uri
+          break
+        end
+      end
+
       raise ImageFetchFailure unless res.is_a?(Net::HTTPSuccess)
+
       res.read_body do |str|
         break if parse_packet(str)
       end

test/test.rb

@@ -139,4 +139,37 @@ class FastImageTest < Test::Unit::TestCase
       FastImage.size(File.join(FixturePath, "faulty.jpg"), :raise_on_failure=>true)
     end
   end
+  
+  def test_should_handle_permanent_redirect
+    url = "http://example.com/foo.jpeg"
+    register_redirect(url, TestUrl + GoodFixtures.keys.first)
+    assert_equal GoodFixtures[GoodFixtures.keys.first][1], FastImage.size(url, :raise_on_failure=>true)
+  end
+
+  def test_should_handle_permanent_redirect_4_times
+    first_url = "http://example.com/foo.jpeg"
+    register_redirect(first_url, "http://example.com/foo2.jpeg")
+    register_redirect("http://example.com/foo2.jpeg", "http://example.com/foo3.jpeg")
+    register_redirect("http://example.com/foo3.jpeg", "http://example.com/foo4.jpeg")
+    register_redirect("http://example.com/foo4.jpeg", TestUrl + GoodFixtures.keys.first)
+    assert_equal GoodFixtures[GoodFixtures.keys.first][1], FastImage.size(first_url, :raise_on_failure=>true)
+  end
+
+  def test_should_raise_on_permanent_redirect_5_times
+    first_url = "http://example.com/foo.jpeg"
+    register_redirect(first_url, "http://example.com/foo2.jpeg")
+    register_redirect("http://example.com/foo2.jpeg", "http://example.com/foo3.jpeg")
+    register_redirect("http://example.com/foo3.jpeg", "http://example.com/foo4.jpeg")
+    register_redirect("http://example.com/foo4.jpeg", "http://example.com/foo5.jpeg")
+    register_redirect("http://example.com/foo5.jpeg", TestUrl + GoodFixtures.keys.first)
+    assert_raises(FastImage::ImageFetchFailure) do
+      FastImage.size(first_url, :raise_on_failure=>true)
+    end
+  end
+  
+  def register_redirect(from, to)
+    resp = Net::HTTPMovedPermanently.new(1.0, 302, "Moved")
+    resp['Location'] = to
+    FakeWeb.register_uri(:get, from, :response=>resp)
+  end
 end