Make sure that home_url can be nil

lib/docs/core/scraper.rb

@@ -3,7 +3,7 @@ require 'set'
 module Docs
   class Scraper < Doc
     class << self
-      attr_accessor :base_url, :home_url, :root_path, :initial_paths, :options, :html_filters, :text_filters
+      attr_accessor :base_url, :root_path, :initial_paths, :options, :html_filters, :text_filters
 
       def inherited(subclass)
         super
@@ -66,7 +66,7 @@ module Docs
     end
 
     def home_url
-      @home_url ||= URL.parse self.class.home_url
+      @home_url ||= URL.parse self.class.home_url if self.class.home_url
     end
 
     def root_path

test/lib/docs/core/doc_test.rb

@@ -60,6 +60,19 @@ class DocsDocTest < MiniTest::Spec
     end
   end
 
+  describe ".home_url" do
+    it "returns nil" do
+      assert_nil doc.home_url
+    end
+  end
+
+  describe ".home_url=" do
+    it "stores .home_url" do
+      doc.home_url = 'http://www.url.com/doc'
+      assert_equal 'http://www.url.com/doc', doc.home_url
+    end
+  end
+  
   describe ".abstract" do
     it "returns nil" do
       assert_nil doc.abstract