Merge pull request rails#46751 from basecamp/action-text-replace-optimization

Avoid unnecessary replacements in action text when the replacement node is unchanged

Author: jonathanhefner

actiontext/lib/action_text/fragment.rb

@@ -37,7 +37,8 @@ def update
     def replace(selector)
       update do |source|
         source.css(selector).each do |node|
-          node.replace(yield(node).to_s)
+          replacement_node = yield(node)
+          node.replace(replacement_node.to_s) if node != replacement_node
         end
       end
     end

actiontext/test/unit/content_test.rb

@@ -134,6 +134,33 @@ class ActionText::ContentTest < ActiveSupport::TestCase
     assert_match %r/\A#{Regexp.escape '<div class="trix-content">'}/, rendered
   end
 
+  test "replace certain nodes" do
+    html = <<~HTML
+      <div>
+        <p>replace me</p>
+        <p>ignore me</p>
+      </div>
+    HTML
+
+    expected_html = <<~HTML
+      <div>
+        <p>replaced</p>
+        <p>ignore me</p>
+      </div>
+    HTML
+
+    content = content_from_html(html)
+    replaced_fragment = content.fragment.replace("p") do |node|
+      if node.text =~ /replace me/
+        "<p>replaced</p>"
+      else
+        node
+      end
+    end
+
+    assert_equal expected_html.strip, replaced_fragment.to_html
+  end
+
   private
     def content_from_html(html)
       ActionText::Content.new(html).tap do |content|