Fix bug in Gollum tags filter

The gollums tag filter is in the wrong place because when it gerates
the image, we have already run the `ImageLazyLoad` filter. This results
in an empty image because it has the wrong attributes.

changelogs/unreleased/fj-fix-bug-gollum-tag-filter.yml

+---
+title: Fix bug in Gollum Tags filter
+merge_request: 56638
+author:
+type: fixed

lib/banzai/filter/gollum_tags_filter.rb

@@ -98,14 +98,15 @@ module Banzai
 
         return unless image?(content)
 
+        path =
           if url?(content)
-          path = content
+            content
           elsif file = wiki.find_file(content, load_content: false)
-          path = ::File.join(wiki_base_path, file.path)
+            file.path
           end
 
         if path
-          content_tag(:img, nil, data: { src: path }, class: 'gfm')
+          content_tag(:img, nil, src: path, class: 'gfm')
         end
       end
 

lib/banzai/pipeline/wiki_pipeline.rb

@@ -5,7 +5,7 @@ module Banzai
     class WikiPipeline < FullPipeline
       def self.filters
         @filters ||= begin
-          super.insert_after(Filter::TableOfContentsFilter, Filter::GollumTagsFilter)
+          super.insert_before(Filter::ImageLazyLoadFilter, Filter::GollumTagsFilter)
                .insert_before(Filter::TaskListFilter, Filter::WikiLinkFilter)
         end
       end

spec/lib/banzai/filter/gollum_tags_filter_spec.rb

@@ -27,7 +27,7 @@ RSpec.describe Banzai::Filter::GollumTagsFilter do
       tag = '[[images/image.jpg]]'
       doc = filter("See #{tag}", wiki: wiki)
 
-      expect(doc.at_css('img')['data-src']).to eq "#{wiki.wiki_base_path}/images/image.jpg"
+      expect(doc.at_css('img')['src']).to eq 'images/image.jpg'
     end
 
     it 'does not creates img tag if image does not exist' do
@@ -45,7 +45,7 @@ RSpec.describe Banzai::Filter::GollumTagsFilter do
       tag = '[[http://example.com/image.jpg]]'
       doc = filter("See #{tag}", wiki: wiki)
 
-      expect(doc.at_css('img')['data-src']).to eq "http://example.com/image.jpg"
+      expect(doc.at_css('img')['src']).to eq "http://example.com/image.jpg"
     end
 
     it 'does not creates img tag for invalid URL' do

spec/lib/banzai/pipeline/wiki_pipeline_spec.rb

@@ -289,4 +289,29 @@ RSpec.describe Banzai::Pipeline::WikiPipeline do
       expect(output).to include('<audio src="/wiki_link_ns/wiki_link_project/-/wikis/nested/twice/audio%20file%20name.wav"')
     end
   end
+
+  describe 'gollum tag filters' do
+    context 'when local image file exists' do
+      it 'sets the proper attributes for the image' do
+        gollum_file_double = double('Gollum::File',
+          mime_type: 'image/jpeg',
+          name: 'images/image.jpg',
+          path: 'images/image.jpg',
+          raw_data: '')
+
+        wiki_file = Gitlab::Git::WikiFile.new(gollum_file_double)
+        markdown = "[[#{wiki_file.path}]]"
+
+        expect(wiki).to receive(:find_file).with(wiki_file.path, load_content: false).and_return(wiki_file)
+
+        output = described_class.to_html(markdown, project: project, wiki: wiki, page_slug: page.slug)
+        doc = Nokogiri::HTML::DocumentFragment.parse(output)
+
+        full_path = "/wiki_link_ns/wiki_link_project/-/wikis/nested/twice/#{wiki_file.path}"
+        expect(doc.css('a')[0].attr('href')).to eq(full_path)
+        expect(doc.css('img')[0].attr('class')).to eq('gfm lazy')
+        expect(doc.css('img')[0].attr('data-src')).to eq(full_path)
+      end
+    end
+  end
 end