Add backend code for searching posts with images.

lib/search.rb

@@ -338,6 +338,10 @@ class Search
     end
   end
 
+  advanced_filter(/in:image/) do |posts|
+    posts.where("posts.image_url IS NOT NULL")
+  end
+
   advanced_filter(/category:(.+)/) do |posts,match|
     exact = false
 

spec/components/search_spec.rb

@@ -632,8 +632,9 @@ describe Search do
       post_uploaded = Fabricate(:post_with_uploaded_image)
       post_with_image_urls = Fabricate(:post_with_image_urls)
       Fabricate(:post)
-      TopicLink.extract_from(post_uploaded)
-      TopicLink.extract_from(post_with_image_urls)
+
+      CookedPostProcessor.new(post_uploaded).update_post_image
+      CookedPostProcessor.new(post_with_image_urls).update_post_image
 
       expect(Search.execute('in:image').posts.map(&:id).sort).to eq([post_uploaded.id, post_with_image_urls.id].sort)
     end