'L{TwistOptions.opt_log_file} exits with L{ExitStatus.EX_IOERR} if
unable to open the log file due to an L{EnvironmentError}.'

def test_logFileCantOpen(self):

    self.patchExit()
    self.patchOpen()
    options = TwistOptions()
    options.opt_log_file('nocanopen')
    self.assertEquals(self.exit.status, ExitStatus.EX_IOERR)
    self.assertTrue(self.exit.message.startswith("Unable    to    open    log    file    'nocanopen':    "))
