Tests - add missing tests of Participants::addParticipant() method for not existing survey

src/Type/ReasonType.php

@@ -12,6 +12,13 @@ use Meritoo\Common\Type\Base\BaseType;
  */
 class ReasonType extends BaseType
 {
+    /**
+     * Reason of exception when there is no survey with given ID
+     *
+     * @var string
+     */
+    const NOT_EXISTING_SURVEY_ID = 'Error: Invalid survey ID';
+
     /**
      * Reason of exception when there is no participants of survey
      *