Selenium-在按钮单击步骤中引发null异常

Question

以下代码正在启动chrome驱动程序，应单击登录按钮。但不要单击登录按钮。在buttonSubmit中引发null异常。使用硒，storyQ 公共课程 { 公共静态IWebDriver驱动程序；

    [FindsBy(How = How.Id, Using = "login-submit")]
    public IWebElement ButtonSubmit;
    static void Main() 
    {    }  

    [Test]
    public void LoginForFirstTime()
    {
         new Story("Login User For First Time")
            .InOrderTo("Verify user can view the features of app after skiping the tour")
            .AsA("LabManager")
            .IWant("To Verify user can view the features of app after skiping the tour")
            .WithScenario("valid user credentials login for first time")
            .Given(NavigateToeDMS)
            .When(Sleepfor30Sec)
            .Then(ClickOnLogin)
            .Execute();
    }

    private void ClickOnLogin()
    {
        ButtonSubmit.Click();
    }

    private void Sleepfor30Sec()
    {
        Thread.Sleep(3000);
    }

    private void NavigateToeDMS()
    {
        var options = new ChromeOptions();
        Driver = new ChromeDriver(options);
        Driver.Navigate().GoToUrl("https://localhost:32768/Identity/Account/Login");
    }


}