如果通过TestNG xml运行，则测试失败并显示NullPointerException，但如果独立运行则测试失败

Question

我有两个测试，我试图通过TestNG xml运行。

如果我独立运行它，它就有效。但是，如果我将它作为带有xml的套件运行，那么第一个测试就会失败并出现NullPointerException as shown here。

package com.Pages;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.How;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

public class LoginPage {

    WebDriver driver;

    @FindBy(how = How.XPATH, using= (".//*[@id='fk-mainbody-id']/div/div/div[1]/div/div[4]/div[2]/input"))
    WebElement email;

    @FindBy(how = How.XPATH, using= (".//*[@id='fk-mainbody-id']/div/div/div[1]/div/div[4]/div[4]/input"))
    WebElement pwd;

    @FindBy(how = How.XPATH, using= (".//*[@id='fk-mainbody-id']/div/div/div[1]/div/div[4]/div[7]/input"))
    WebElement loginbtn;

    @FindBy(how = How.LINK_TEXT, using= ("My Account"))
    WebElement myAccount;

    public LoginPage (WebDriver driver) {
        this.driver = driver;
    }

    public void enteremail (String Userid) {
        email.sendKeys(Userid);
    }

    public  void enterpwd(String passwd) {
        pwd.sendKeys(passwd);
    }

    public void clickLoginButton() {
        loginbtn.click();   
    }

    public boolean checkMyAccount() {  
        WebDriverWait wait = new WebDriverWait(driver,30);
        wait.until(ExpectedConditions.visibilityOf(myAccount));
        return myAccount.isDisplayed();
    }

}

package com.TestCases;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;

public class TestBase {

    WebDriver driver;

    @BeforeTest
    public void invokeBrowser() {
        driver = new FirefoxDriver();
        driver.get("https://www.flipkart.com");
        driver.manage().window().maximize();    
    }

    @AfterTest
    public void teardown() {
        driver.quit();
    }

}

package com.TestCases;

import org.openqa.selenium.support.PageFactory;
import org.testng.Assert;
import org.testng.annotations.Test;
import com.Pages.HomePage;

public class VerifyHomePage extends TestBase 
{

    @Test
    public void VerifyHomePageTitle() throws InterruptedException {
        HomePage hpage = PageFactory.initElements(driver,HomePage.class);
        System.out.println("Test Pass");
        Assert.assertEquals(driver.getTitle(), "Online Shopping India | Buy Mobiles, Electronics, Appliances, Clothing and More Online at Flipkart.com");
        hpage.clicklogin();
    }

}

package com.TestCases;

import org.testng.annotations.Test;
import org.openqa.selenium.support.PageFactory;
import org.testng.Assert;
import com.Pages.HomePage;
import com.Pages.LoginPage;

public class VerifyLogin extends TestBase {

    @Test
    public void checkLoginfunction() throws InterruptedException {
        HomePage hpage = PageFactory.initElements(driver,HomePage.class);
        hpage.clicklogin();
        LoginPage loginp = PageFactory.initElements(driver,LoginPage.class);
        loginp.enteremail("shreshtha.thakre@gmail.com");
        loginp.enterpwd("Shreshtha!1");
        loginp.clickLoginButton();
        loginp.checkMyAccount();
        Assert.assertTrue(loginp.checkMyAccount());
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Parallel test suite">
    <test name="Test">
        <classes>
            <class name="com.TestCases.VerifyHomePage"/>
            <class name="com.TestCases.VerifyLogin"/> 
        </classes>
    </test> <!-- Test -->
</suite> <!-- Suite -->

function square (x) {return x * x;}
function add3 (x) {return x + 3;}

   function chainer(a) {
     return function (b) {
       for(var i = 0; i < a.length; i++) {
        return a[i](b)
        }
      }
   } 
  console.log(chainer([square, add3])(4));