ISAICP-9492: Test coverage

tests/features/joinup_core/css_js_assets.feature

+@api @group-d
+Feature:
+  When script kiddies are fetching the path of some outdated CSS / JS library
+  group, our system returns empty file responses instead of throwing and logging
+  errors.
+
+  Scenario Outline:
+    Given there are no preexisting log records on the site
+    And I go to "/sites/default/files/<asset url>"
+    Then the response status code should be 200
+    And there should be 0 log records
+
+    Examples:
+      # The value of the "include" query string is the gz-compressed, base64
+      # encoded list of the libraries which should be injected into the page.
+      | asset url                                                                                                                        |
+      # CSS - library: system/base.
+      | css/css_notahash.css?delta=50&language=en&theme=ventuno&include=eJwrriwuSc3VT0osTgUAG5MEcA                                       |
+      # JS - at delta=0, there is an external library.
+      | js/js_notahahsh.js?delta=0&language=en&theme=ventuno&include=eJzLT40vT00qyc_PKdZPKSotSMzRg_F1i3MTi0py8hNTUosAOvcPwg&scope=header |

web/modules/custom/joinup_event/joinup_event.module

@@ -190,6 +190,9 @@ function joinup_event_library_info_alter(array &$libraries, string $extension):
   // Temporary support for Internet Explorer.
   // @see https://citnet.tech.ec.europa.eu/CITnet/jira/browse/ISAICP-5564
   // @see https://github.com/openeuropa/oe_webtools/pull/104
+  // This override also used in the test css_js_asset.feature. Please add a
+  // replacement library with an external JS asset for the test HTML head when
+  // this alteration is removed.
   if ($extension === 'oe_webtools') {
     $libraries['drupal.webtools-smartloader']['header'] = TRUE;
   }