Identify frontmatter code blocks when rendering Markdown

lib/banzai/filter/front_matter_filter.rb

@@ -9,7 +9,7 @@ module Banzai
         html.sub(Gitlab::FrontMatter::PATTERN) do |_match|
           lang = $~[:lang].presence || lang_mapping[$~[:delim]]
 
-          ["```#{lang}", $~[:front_matter], "```", "\n"].join("\n")
+          ["```#{lang}:frontmatter", $~[:front_matter], "```", "\n"].join("\n")
         end
       end
     end

lib/banzai/filter/syntax_highlight_filter.rb

@@ -28,6 +28,7 @@ module Banzai
       def highlight_node(node)
         css_classes = +'code highlight js-syntax-highlight'
         lang, lang_params = parse_lang_params(node.attr('lang'))
+        sourcepos = node.parent.attr('data-sourcepos')
         retried = false
 
         if use_rouge?(lang)
@@ -55,7 +56,9 @@ module Banzai
           retry
         end
 
-        highlighted = %(<pre class="#{css_classes}"
+        sourcepos_attr = sourcepos ? "data-sourcepos=\"#{sourcepos}\"" : ""
+
+        highlighted = %(<pre #{sourcepos_attr} class="#{css_classes}"
                              lang="#{language}"
                              #{lang_params}
                              v-pre="true"><code>#{code}</code></pre>)

spec/lib/banzai/filter/front_matter_filter_spec.rb

@@ -39,7 +39,7 @@ RSpec.describe Banzai::Filter::FrontMatterFilter do
 
     aggregate_failures do
       expect(output).not_to include '---'
-      expect(output).to include "```yaml\nfoo: :foo_symbol\n"
+      expect(output).to include "```yaml:frontmatter\nfoo: :foo_symbol\n"
     end
   end
 
@@ -59,7 +59,7 @@ RSpec.describe Banzai::Filter::FrontMatterFilter do
 
     aggregate_failures do
       expect(output).not_to include '+++'
-      expect(output).to include "```toml\nfoo = :foo_symbol\n"
+      expect(output).to include "```toml:frontmatter\nfoo = :foo_symbol\n"
     end
   end
 
@@ -81,7 +81,7 @@ RSpec.describe Banzai::Filter::FrontMatterFilter do
 
     aggregate_failures do
       expect(output).not_to include ';;;'
-      expect(output).to include "```json\n{\n  \"foo\": \":foo_symbol\",\n"
+      expect(output).to include "```json:frontmatter\n{\n  \"foo\": \":foo_symbol\",\n"
     end
   end
 
@@ -101,7 +101,7 @@ RSpec.describe Banzai::Filter::FrontMatterFilter do
 
     aggregate_failures do
       expect(output).not_to include '---arbitrary'
-      expect(output).to include "```arbitrary\nfoo = :foo_symbol\n"
+      expect(output).to include "```arbitrary:frontmatter\nfoo = :foo_symbol\n"
     end
   end
 
@@ -130,7 +130,7 @@ RSpec.describe Banzai::Filter::FrontMatterFilter do
 
       aggregate_failures do
         expect(output).to eq <<~MD
-          ```yaml
+          ```yaml:frontmatter
           foo: :foo_symbol
           bar: :bar_symbol
           ```

spec/lib/banzai/filter/syntax_highlight_filter_spec.rb

@@ -98,6 +98,14 @@ RSpec.describe Banzai::Filter::SyntaxHighlightFilter do
     end
   end
 
+  context "when sourcepos metadata is available" do
+    it "includes it in the highlighted code block" do
+      result = filter('<pre data-sourcepos="1:1-3:3"><code lang="plaintext">This is a test</code></pre>')
+
+      expect(result.to_html).to eq('<pre data-sourcepos="1:1-3:3" class="code highlight js-syntax-highlight language-plaintext" lang="plaintext" v-pre="true"><code><span id="LC1" class="line" lang="plaintext">This is a test</span></code></pre>')
+    end
+  end
+
   context "when Rouge lexing fails" do
     before do
       allow_next_instance_of(Rouge::Lexers::Ruby) do |instance|

spec/lib/banzai/pipeline/pre_process_pipeline_spec.rb

@@ -20,7 +20,7 @@ RSpec.describe Banzai::Pipeline::PreProcessPipeline do
     aggregate_failures do
       expect(result[:output]).not_to include "\xEF\xBB\xBF"
       expect(result[:output]).not_to include '---'
-      expect(result[:output]).to include "```yaml\nfoo: :foo_symbol\n"
+      expect(result[:output]).to include "```yaml:frontmatter\nfoo: :foo_symbol\n"
       expect(result[:output]).to include "> blockquote\n"
     end
   end