Add DSL for urls

test/serializers/urls_test.rb

@@ -0,0 +1,26 @@
+require 'test_helper'
+
+module ActiveModel
+  class Serializer
+    class UrlsTest < Minitest::Test
+
+      def setup
+        @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+        @post = Post.new({ title: 'New Post', body: 'Body' })
+        @comment = Comment.new({ id: 1, body: 'ZOMG A COMMENT' })
+        @post.comments = [@comment]
+
+        @profile_serializer = ProfileSerializer.new(@profile)
+        @post_serializer = PostSerializer.new(@post)
+      end
+
+      def test_urls_definition
+        assert_equal([:posts, :comments], @profile_serializer.class._urls)
+      end
+
+      def test_url_definition
+        assert_equal([:comments], @post_serializer.class._urls)
+      end
+    end
+  end
+end