Modify create_personal_snippet_spec to verify code highlighting

See https://gitlab.com/gitlab-org/quality/testcases/-/issues/899

qa/qa/page/component/snippet.rb

@@ -154,6 +154,12 @@ module QA
           end
         end
 
+        def has_syntax_highlighting?(language)
+          within_element(:file_content) do
+            find('.line')['lang'].to_s == language
+          end
+        end
+
         def edit_comment(comment)
           finished_loading?
           click_element(:edit_comment_button)

qa/qa/specs/features/browser_ui/3_create/snippet/create_personal_snippet_spec.rb

@@ -14,16 +14,17 @@ module QA
           snippet.title = 'Snippet title'
           snippet.description = 'Snippet description'
           snippet.visibility = 'Private'
-          snippet.file_name = 'New snippet file name'
-          snippet.file_content = 'Snippet file text'
+          snippet.file_name = 'ruby_file.rb'
+          snippet.file_content = 'File.read("test.txt").split(/\n/)'
         end
 
         Page::Dashboard::Snippet::Show.perform do |snippet|
           expect(snippet).to have_snippet_title('Snippet title')
           expect(snippet).to have_snippet_description('Snippet description')
           expect(snippet).to have_visibility_type(/private/i)
-          expect(snippet).to have_file_name('New snippet file name')
-          expect(snippet).to have_file_content('Snippet file text')
+          expect(snippet).to have_file_name('ruby_file.rb')
+          expect(snippet).to have_file_content('File.read("test.txt").split(/\n/)')
+          expect(snippet).to have_syntax_highlighting('ruby')
         end
       end
     end