new_contents: import pytest
  
  from bokeh.command.bootstrap import main
  
  def test_no_subcommand(capsys):
      with pytest.raises(SystemExit):
          main(["bokeh"])
      out, err = capsys.readouterr()
      assert err == "ERROR: Must specify subcommand, one of: html, json or serve\n"
      assert out == ""
  
subject: Test running `bokeh` with no subcommand