Merge pull request #264 from hjwp/chapter-15-tests

Enable tests for chapter 15, finalise listings

Author: Xronophobe

.github/workflows/tests.yml

@@ -28,7 +28,7 @@ jobs:
           test_chapter_12_organising_test_files,
           test_chapter_13_database_layer_validation,
           test_chapter_14_simple_form,
-          # test_chapter_15_advanced_forms,
+          test_chapter_15_advanced_forms,
           test_chapter_16_javascript,
           unit-test
         ]