FIX: non-oneboxed links on separate lines should stay on separate lines

lib/oneboxer.rb

@@ -77,6 +77,8 @@ def self.each_onebox_link(string_or_doc)
     doc
   end
 
+  HTML5_BLOCK_ELEMENTS ||= %w{address article aside blockquote canvas center dd div dl dt fieldset figcaption figure footer form h1 h2 h3 h4 h5 h6 header hgroup hr li main nav noscript ol output p pre section table tfoot ul video}
+
   def self.apply(string_or_doc, args = nil)
     doc = string_or_doc
     doc = Nokogiri::HTML::fragment(doc) if doc.is_a?(String)
@@ -88,8 +90,9 @@ def self.apply(string_or_doc, args = nil)
         parsed_onebox = Nokogiri::HTML::fragment(onebox)
         next unless parsed_onebox.children.count > 0
 
-        # special logic to strip empty p elements
-        if element&.parent&.node_name&.downcase == "p" && element&.parent&.children&.count == 1
+        if element&.parent&.node_name&.downcase == "p" &&
+           element.parent.children.count == 1 &&
+           HTML5_BLOCK_ELEMENTS.include?(parsed_onebox.children[0].node_name.downcase)
           element = element.parent
         end
 
@@ -98,6 +101,9 @@ def self.apply(string_or_doc, args = nil)
       end
     end
 
+    # strip empty <p> elements
+    doc.css("p").each { |p| p.remove if p.children.empty? }
+
     Result.new(doc, changed)
   end
 

spec/components/oneboxer_spec.rb

@@ -103,7 +103,7 @@ def preview(url, user = nil, category = nil, topic = nil)
       post = Fabricate(:post, raw: Discourse.base_url + "/new?'class=black")
       cpp = CookedPostProcessor.new(post, invalidate_oneboxes: true)
       cpp.post_process_oneboxes
-      expect(cpp.html).to eq("<a href=\"#{Discourse.base_url}/new?%27class=black\">http://test.localhost/new?%27class=black</a>")
+      expect(cpp.html).to eq("<p><a href=\"#{Discourse.base_url}/new?%27class=black\">http://test.localhost/new?%27class=black</a></p>")
     end
   end