您仅将 WebDriver 实例声明为：
public WebDriver driver;
您还需要按以下方式对其进行初始化：
driver = new FirefoxDriver();
FirefoxOptions()有效代码块的实例将是：
System.setProperty("webdriver.firefox.driver","C:\Users\Nabila\Downloads\geckodriver-v0.26.0-win64\geckodriver.exe");FirefoxOptions options = new FirefoxOptions();options.addArguments("test-type");options.addArguments("start-maximized");options.addArguments("--js-flags=--expose-gc"); options.addArguments("--enable-precise-memory-info"); options.addArguments("--disable-popup-blocking");options.addArguments("--disable-default-apps");options.addArguments("test-type=browser");options.addArguments("disable-infobars");driver = new FirefoxDriver(options);driver.navigate().to("http://www.demo.guru99.com/V4/");driver.manage().timeouts().implicitlyWait(300, TimeUnit.SECONDS);
