FIX: Optimize images in Onebox (#8471)

This commit ensures that images in Onebox are being optimized, but not
converted to lightbox too.

lib/cooked_post_processor.rb

@@ -206,9 +206,7 @@ class CookedPostProcessor
     # minus data images
     @doc.css("img[src^='data']") -
     # minus emojis
-    @doc.css("img.emoji") -
-    # minus oneboxed images
-    oneboxed_images
+    @doc.css("img.emoji")
   end
 
   def extract_images_for_post
@@ -346,7 +344,10 @@ class CookedPostProcessor
       end
     end
 
-    add_lightbox!(img, original_width, original_height, upload, cropped: crop) if img.ancestors('.quote').blank?
+    if img.ancestors('.onebox, .onebox-body, .quote').blank? && !img.classes.include?("onebox")
+      add_lightbox!(img, original_width, original_height, upload, cropped: crop)
+    end
+
     optimize_image!(img, upload, cropped: crop) if upload
   end
 

spec/components/cooked_post_processor_spec.rb

@@ -946,6 +946,21 @@ describe CookedPostProcessor do
       expect(doc.css('.lightbox-wrapper').size).to eq(0)
       expect(doc.css('img').first['srcset']).to_not eq(nil)
     end
+
+    it "optimizes images in Onebox" do
+      Oneboxer.expects(:onebox)
+        .with("https://discourse.org", anything)
+        .returns("<aside class='onebox'><img src='#{upload.url}' width='512' height='384'></aside>")
+
+      post = Fabricate(:post, raw: "https://discourse.org")
+
+      cpp = CookedPostProcessor.new(post, disable_loading_image: true)
+      cpp.post_process
+
+      doc = Nokogiri::HTML::fragment(cpp.html)
+      expect(doc.css('.lightbox-wrapper').size).to eq(0)
+      expect(doc.css('img').first['srcset']).to_not eq(nil)
+    end
   end
 
   context "#post_process_oneboxes" do