# File lib/redis/client.rb, line 515
        def check(client)
          # Check the instance is really of the role we are looking for.
          # We can't assume the command is supported since it was introduced
          # recently and this client should work with old stuff.
          begin
            role = client.call([:role])[0]
          rescue Redis::CommandError
            # Assume the test is passed if we can't get a reply from ROLE...
            role = @role
          end

          if role != @role
            client.disconnect
            raise ConnectionError, "Instance role mismatch. Expected #{@role}, got #{role}."
          end
        end