Render unknown tags (verbatim: true) as-is

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Changelog
 
+- Unknown tags which are parsed with `verbatim: true` are rendered as-is.
 - Handle image links with titles.
 
 ## 0.5.0

lib/markdown_formatter/renderer.ex

@@ -161,6 +161,9 @@ defmodule MarkdownFormatter.Renderer do
       doc
       |> push([with_depth(opts.prefix, opts.depth - 1), render(contents, Q.new(), opts)])
 
+  defp render({tag, [], [contents], %{verbatim: true}}, doc, _opts) when is_binary(contents),
+    do: push(doc, ["<#{tag}>\n#{contents}\n</#{tag}>"])
+
   # text node
   defp render([text], @empty_queue, opts) when is_binary(text), do: text |> reformat(opts)
   defp render(text, @empty_queue, opts) when is_binary(text), do: text |> reformat(opts)

test/markdown_formatter/renderer_test.exs

@@ -216,6 +216,25 @@ defmodule MarkdownFormatter.RendererTest do
       > You should read me.
       """)
     end
+
+    test "renders collapsible items" do
+      """
+      <details>
+      <summary>Preview title</summary>
+
+      Some extra content.
+      </details>
+      """
+      |> parse!()
+      |> Renderer.to_markdown()
+      |> assert_eq("""
+      <details>
+      <summary>Preview title</summary>
+
+      Some extra content.
+      </details>
+      """)
+    end
   end
 
   describe "to_markdown documents" do