Add a blank richtext description method

lib/rich_text.rb

@@ -57,6 +57,10 @@ module RichText
       nil
     end
 
+    def description
+      nil
+    end
+
     protected
 
     def simple_format(text)

test/lib/rich_text_test.rb

@@ -250,16 +250,18 @@ class RichTextTest < ActiveSupport::TestCase
     assert_equal 141, r.spam_score.round
   end
 
-  def test_text_no_image
+  def test_text_no_opengraph_properties
     r = RichText.new("text", "foo https://example.com/ bar")
     assert_nil r.image
     assert_nil r.image_alt
+    assert_nil r.description
   end
 
-  def test_html_no_image
+  def test_html_no_opengraph_properties
     r = RichText.new("html", "foo <a href='https://example.com/'>bar</a> baz")
     assert_nil r.image
     assert_nil r.image_alt
+    assert_nil r.description
   end
 
   def test_markdown_no_image
@@ -328,6 +330,11 @@ class RichTextTest < ActiveSupport::TestCase
     assert_equal "have src", r.image_alt
   end
 
+  def test_markdown_no_description
+    r = RichText.new("markdown", "#Nope")
+    assert_nil r.description
+  end
+
   private
 
   def assert_html(richtext, &block)