Add extraction of upload extension. Add rspec test for search of post

with upload by extension.

app/models/topic_link.rb

@@ -164,7 +164,7 @@ SQL
           added_urls << url
 
           unless TopicLink.exists?(topic_id: post.topic_id, post_id: post.id, url: url)
-            file_extension = File.extname(parsed.path)[1..5].downcase unless File.extname(parsed.path).empty?
+            file_extension = File.extname(parsed.path)[1..10].downcase unless File.extname(parsed.path).empty?
             begin
               TopicLink.create!(post_id: post.id,
                                 user_id: post.user_id,

lib/upload_creator.rb

@@ -73,6 +73,7 @@ class UploadCreator
       @upload.sha1              = sha1
       @upload.url               = ""
       @upload.origin            = @opts[:origin][0...1000] if @opts[:origin]
+      @upload.extension         = File.extname(@filename)[1..10]
 
       if FileHelper.is_image?(@filename)
         @upload.width, @upload.height = ImageSizer.resize(*@image_info.size)

spec/components/search_spec.rb

@@ -712,14 +712,16 @@ describe Search do
                          raw: "Discourse logo\n"\
                               "https://www.discourse.org/a/img/favicon.png\n"\
                               "https://www.discourse.org/a/img/trust-1x.jpg")
+      post_with_upload = Fabricate(:post)
+      post_with_upload.uploads = [Fabricate(:upload)]
       Fabricate(:post)
 
       TopicLink.extract_from(post1)
       TopicLink.extract_from(post2)
 
       expect(Search.execute('filetype:jpg').posts.map(&:id)).to eq([post2.id])
-      expect(Search.execute('filetype:png').posts.map(&:id)).to contain_exactly(post1.id, post2.id)
-      expect(Search.execute('logo filetype:jpg').posts.map(&:id)).to eq([post2.id])
+      expect(Search.execute('filetype:png').posts.map(&:id)).to contain_exactly(post1.id, post2.id, post_with_upload.id)
+      expect(Search.execute('logo filetype:png').posts.map(&:id)).to eq([post2.id])
     end
   end
 

spec/fabricators/upload_fabricator.rb

@@ -6,6 +6,7 @@ Fabricator(:upload) do
   width 100
   height 200
   url { sequence(:url) { |n| "/uploads/default/#{n}/1234567890123456.png" } }
+  extension "png"
 end
 
 Fabricator(:upload_s3, from: :upload) do