Add pre commit hook

package.json

@@ -34,7 +34,7 @@
   },
   "husky": {
     "hooks": {
-      "pre-commit": "./scripts/hooks/apply-formatters.sh && ./scripts/hooks/remove-test-prefixes.sh && ./scripts/hooks/generate-docu.sh"
+      "pre-commit": "./scripts/hooks/apply-formatters.sh && ./scripts/hooks/remove-test-prefixes.sh && ./scripts/hooks/generate-docu.sh && ./scripts/hooks/prevent-illegal-characters.sh"
     }
   }
 }

scripts/hooks/prevent-illegal-characters.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+# Checks and aborts the commit:
+#   if (there are files which contain merge conflict markers)
+#   OR if (`window.addEventListener` is used 
+#           in other files other than EventListenerHelper class)
+# conflict_markers = ['<<<<<<<','=======','>>>>>>>']
+# Run this script only from Luigi root folder, else not all files will be checked
+# ./scripts/hooks/prevent-illegal-characters.sh
+
+
+function check_conflict_marker() { 
+    declare -a illegal_strings=("<<<<<<<" "=======" ">>>>>>>")
+    # string diff containing changes already staged for commit
+    staged_changes=$(git diff --cached --diff-filter=ACMR -- . ':(exclude)scripts/hooks/prevent-illegal-characters.sh')
+
+    for illegal in ${illegal_strings[@]}; do
+        if [[ $staged_changes == *$illegal*   ]]; then
+            echo "Found illegal string: $illegal"
+            echo "Aborting commit!"
+            exit 1
+        fi
+    done
+}
+
+function check_addEventListener_wrong_usage() { 
+    # git search query returning file names that used window.addEventListener illegally
+    illegal_files=$(git diff  --cached --diff-filter=ACMR \
+                    -G 'window.addEventListener' --name-only  -- core \
+                    ':(exclude)scripts/hooks/prevent-illegal-characters.sh' \
+                    ':(exclude)core/src/utilities/helpers/event-listener-helpers.js')
+    if [ -n "$illegal_files" ]; then
+        echo "The following files should not contain 'window.addEventListener':"
+        echo -e "\033[1;31m$illegal_files\033[0m"
+        echo "Aborting commit!"
+        exit 1
+    fi
+}
+
+check_conflict_marker
+
+check_addEventListener_wrong_usage