trait CKEditor5ValidationTestTrait

trait CKEditor5ValidationTestTrait {
    
    /**
     * Decorator for CKEditor5::validatePair() that returns an assertable array.
     *
     * @param \Drupal\editor\EditorInterface $text_editor
     *   The paired text editor to validate.
     * @param \Drupal\filter\FilterFormatInterface $text_format
     *   The paired text format to validate.
     * @param bool $all_compatibility_problems
     *   Only fundamental compatibility violations are returned unless TRUE.
     *
     * @return array
     *   An array with property paths as keys and violation messages as values.
     *
     * @see \Drupal\ckeditor5\Plugin\Editor\CKEditor5::validatePair
     */
    private function validatePairToViolationsArray(EditorInterface $text_editor, FilterFormatInterface $text_format, bool $all_compatibility_problems) : array {
        $violations = CKEditor5::validatePair($text_editor, $text_format, $all_compatibility_problems);
        $actual_violations = [];
        foreach ($violations as $violation) {
            if (!isset($actual_violations[$violation->getPropertyPath()])) {
                $actual_violations[$violation->getPropertyPath()] = (string) $violation->getMessage();
            }
            else {
                // Transform value from string to array.
                if (is_string($actual_violations[$violation->getPropertyPath()])) {
                    $actual_violations[$violation->getPropertyPath()] = (array) $actual_violations[$violation->getPropertyPath()];
                }
                // And append.
                $actual_violations[$violation->getPropertyPath()][] = (string) $violation->getMessage();
            }
        }
        return $actual_violations;
    }

}