public function testAuthIsForcedIfCredentialsSet()
 {
     $conn = new Swift_Connection_SMTP();
     $this->assertFalse($conn->hasExtension("AUTH"));
     $conn->setUsername("xxx");
     $conn->setPassword("yyyy");
     try {
         $conn->postConnect(new Swift($conn, "xxx", Swift::NO_START));
     } catch (Exception $e) {
     }
     $this->assertTrue($conn->hasExtension("AUTH"));
 }