Public keyword is not needed.

tests/unit/MigratorCest.php

@@ -3,16 +3,16 @@ use \UnitTester;
 use \MailPoet\Config\Migrator;
 
 class MigratorCest {
-  public function _before() {
+  function _before() {
     $this->migrator = new Migrator();
   }
 
-  public function itCanGenerateTheSubscriberSql() {
+  function itCanGenerateTheSubscriberSql() {
     $subscriber_sql = $this->migrator->subscriber();
     $expected_table = $this->migrator->prefix . 'subscriber';
     expect($subscriber_sql)->contains($expected_table);
   }
 
-  public function _after() {
+  function _after() {
   }
 }