'This method composes the nosetests command to send to the terminal. If nosetests aren\'t being run,
the command returns None.'

@property
def cmd(self):

    if (not self.test_spec):
        test_spec = self.test_dir
    else:
        test_spec = (self.test_dir / self.test_spec)
    if self.serversonly:
        return None
    cmd = (['DEFAULT_STORE={}'.format(self.default_store), "SCREENSHOT_DIR='{}'".format(self.log_dir), "BOK_CHOY_HAR_DIR='{}'".format(self.har_dir), "BOKCHOY_A11Y_CUSTOM_RULES_FILE='{}'".format(self.a11y_file), "SELENIUM_DRIVER_LOG_DIR='{}'".format(self.log_dir), "VERIFY_XSS='{}'".format(self.verify_xss), 'nosetests', test_spec] + self.verbosity_processes_command)
    if self.save_screenshots:
        cmd.append('--with-save-baseline')
    if self.extra_args:
        cmd.append(self.extra_args)
    cmd.extend(self.passthrough_options)
    return cmd
