new_contents: import pytest
  
  from ceph_deploy.cli import get_parser
  
  
  class TestParserPurge(object):
  
      def setup(self):
          self.parser = get_parser()
  
      def test_purge_help(self, capsys):
          with pytest.raises(SystemExit):
              self.parser.parse_args('purge --help'.split())
          out, err = capsys.readouterr()
          assert 'usage: ceph-deploy purge' in out
          assert 'positional arguments:' in out
          assert 'optional arguments:' in out
  
      def test_purge_host_required(self, capsys):
          with pytest.raises(SystemExit):
              self.parser.parse_args('purge'.split())
          out, err = capsys.readouterr()
          assert "error: too few arguments" in err
  
      def test_purge_one_host(self):
          args = self.parser.parse_args('purge host1'.split())
          assert args.host == ['host1']
  
      def test_purge_multiple_hosts(self):
          hostnames = ['host1', 'host2', 'host3']
          args = self.parser.parse_args(['purge'] + hostnames)
          assert frozenset(args.host) == frozenset(hostnames)
  
subject: Add tests for argparse purge