'L{TwistOptions.selectDefaultLogObserver} will not override an already
selected observer.'

def test_selectDefaultLogObserverDefaultWithoutTTY(self):

    self.patchOpen()
    options = TwistOptions()
    options.opt_log_file('queso')
    options.selectDefaultLogObserver()
    self.assertIdentical(options['fileLogObserverFactory'], jsonFileLogObserver)
    self.assertEqual(options['logFormat'], 'json')
