Add new scrubber suitable for strip tags but adding whitespace

lib/rails/html/scrubbers.rb

@@ -195,5 +195,33 @@ def scrub(node)
         end
       end
     end
+
+    # === Rails::HTML::SpaceBlockElementScrubber
+    #
+    # +Rails::HTML::SpaceBlockElementScrubber+ removes all undisplayable tags and contents.
+    #
+    # It preserves text contents and inserts a space around block level elements.
+    class SpaceBlockElementScrubber < Loofah::Scrubber # :nodoc:
+      def initialize
+        @direction = :bottom_up
+      end
+
+      def scrub(node)
+        if Loofah::Elements::LINEBREAKERS.include?(node.name)
+          replacement = if Loofah::Elements::INLINE_LINE_BREAK.include?(node.name)
+            " "
+          else
+            " #{node.content} "
+          end
+          node.add_next_sibling(Nokogiri::XML::Text.new(replacement, node.document))
+          node.remove
+        elsif node.text?
+          CONTINUE
+        else
+          node.before node.children
+          node.remove
+        end
+      end
+    end
   end
 end

test/scrubbers_test.rb

@@ -200,6 +200,20 @@ def test_skips_text_nodes
   end
 end
 
+class SpaceBlockElementScrubberTest < ScrubberTest
+  def setup
+    @scrubber = Rails::HTML::SpaceBlockElementScrubber.new
+  end
+
+  def test_removes_all_tags_and_keeps_the_text_content_and_adds_spaces
+    assert_scrubbed %(<div><h1>A list!</h1><ul><li>An element!</li></ul><script>alert("hi!")</script></div>), "  A list!   An element!   "
+  end
+
+  def test_skips_text_nodes
+    assert_node_skipped("some text")
+  end
+end
+
 class ReturningStopFromScrubNodeTest < ScrubberTest
   class ScrubStopper < Rails::HTML::PermitScrubber
     def scrub_node(node)