public function test_appending_new_recipients_to_existing_recipients()
 {
     $email = new BP_Email('activity-at-message');
     $original_recipient = '*****@*****.**';
     $new_recipient = '*****@*****.**';
     $email->set_to($original_recipient);
     $addresses = $email->get_to();
     $this->assertSame($original_recipient, $addresses[0]->get_address());
     $email->set_to($new_recipient, '', 'add');
     $addresses = $email->get_to();
     $this->assertSame($original_recipient, $addresses[0]->get_address());
     $this->assertSame($new_recipient, $addresses[1]->get_address());
 }