new_contents: """
  The tests provided in this module make sure that the server
  instance behaves as expected.
  """
  
  import pytest
  
  from saltyrtc import server
  
  
  class TestServer:
      @pytest.mark.asyncio
      def test_repeated_permanent_keys(self, server_permanent_keys):
          """
          Ensure the server does not accept repeated keys.
          """
          keys = server_permanent_keys + [server_permanent_keys[1]]
          with pytest.raises(server.ServerKeyError) as exc_info:
              yield from server.serve(None, keys)
          assert 'Repeated permanent keys' in str(exc_info.value)
  
subject: Add test for repeated permanent keys on a Server class instance