Support "Preview" tab also for commit commands

app/services/preview_markdown_service.rb

@@ -16,7 +16,7 @@ class PreviewMarkdownService < BaseService
   private
 
   def explain_quick_actions(text)
-    return text, [] unless %w(Issue MergeRequest).include?(commands_target_type)
+    return text, [] unless %w(Issue MergeRequest Commit).include?(commands_target_type)
 
     quick_actions_service = QuickActions::InterpretService.new(project, current_user)
     quick_actions_service.explain(text, find_commands_target)
@@ -29,13 +29,9 @@ class PreviewMarkdownService < BaseService
   end
 
   def find_commands_target
-    if commands_target_id.present?
-      finder = commands_target_type == 'Issue' ? IssuesFinder : MergeRequestsFinder
-      finder.new(current_user, project_id: project.id).find(commands_target_id)
-    else
-      collection = commands_target_type == 'Issue' ? project.issues : project.merge_requests
-      collection.build
-    end
+    Projects::AutocompleteService
+      .new(project, current_user)
+      .target(commands_target_type, commands_target_id)
   end
 
   def commands_target_type

spec/services/preview_markdown_service_spec.rb

@@ -65,6 +65,31 @@ describe PreviewMarkdownService do
     end
   end
 
+  context 'commit description' do
+    let(:project) { create(:project, :repository) }
+    let(:commit) { project.commit }
+    let(:params) do
+      {
+        text: "My work\n/tag v1.2.3 Stable release",
+        quick_actions_target_type: 'Commit',
+        quick_actions_target_id: commit.id
+      }
+    end
+    let(:service) { described_class.new(project, user, params) }
+
+    it 'removes quick actions from text' do
+      result = service.execute
+
+      expect(result[:text]).to eq 'My work'
+    end
+
+    it 'explains quick actions effect' do
+      result = service.execute
+
+      expect(result[:commands]).to eq 'Tags this commit to v1.2.3 with "Stable release".'
+    end
+  end
+
   it 'sets correct markdown engine' do
     service = described_class.new(project, user, { markdown_version: CacheMarkdownField::CACHE_REDCARPET_VERSION })
     result  = service.execute