使用Selenium Web Driver运行测试脚本Page Object Model时出现java.lang.NullPointerException异常

Question

package com.qa.base;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Properties;
import java.util.concurrent.TimeUnit;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

import com.qa.util.TestUitl;

public class TestBase {

    public static WebDriver driver;

    public static Properties prop;

    // Creating a Constructor
    public TestBase() {

        prop = new Properties();

        try {
            File file = new File("/APIAutomation/CRMTest/src/main/java/com/qa/config/config.properties");

            FileInputStream fis = new FileInputStream(file);

            prop.load(fis);

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
    
    public static void initializtion() {
        
        String browser = prop.getProperty("browser");
        
        if(browser.equals("chrome")) {
            System.setProperty("webdriver.chrome.driver", "C:/APIAutomation/chromedriver.exe");
            driver = new ChromeDriver();
        }
        
        else
        {
            System.out.println("Quit Running Script");
        }
        
        driver.manage().window().maximize();
        driver.manage().deleteAllCookies();
    
        driver.manage().timeouts().implicitlyWait(TestUitl.PAGE_LOAD_TIMEOUT, TimeUnit.SECONDS);
        driver.manage().timeouts().implicitlyWait(TestUitl.IMPLICIT_WAIT, TimeUnit.SECONDS);
        driver.get(prop.getProperty("url"));
        
        
    }
}

Page Factory
package com.qa.pages;

import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;

import com.qa.base.TestBase;

public class loginPage extends TestBase{
    
    //Page Factory
        @FindBy(name="email")
        WebElement email;
        
        @FindBy(name="password")
        WebElement password;
        
        @FindBy(xpath=".//div[@class='ui fluid large blue submit button']")
        WebElement loginButton;
        
        @FindBy(xpath="//div[@class ='column']/div[2][@class='ui message']")
        WebElement OldLogin;
        
        //Initialization the Page Object
        
        public loginPage() {
            PageFactory.initElements(driver, this);
        }
        
        //Actions
        
        public String validateLoginPageTitle() {
            return driver.getTitle();
            
        }
        
        public String validateUserName() {
            
            return OldLogin.getText();
            
            
        }
        
        public HomePage login(String user, String pass) {
            
            email.sendKeys(user);
            password.sendKeys(pass);
            loginButton.click();
            
            return new HomePage();
        }
    }



Page Factory HomePage
package com.qa.pages;


import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;

import com.qa.base.TestBase;

public class HomePage extends TestBase{
    
    //PageFactory
        @FindBy(xpath = ".//div[@id='main-nav']/a[@href='/home']")
        WebElement Homepage;
        
        @FindBy(xpath =".//div/span[@class='user-display']")
        WebElement username;
        
        @FindBy(xpath =".//span[contains(text(),'Contacts')]")
        WebElement contactlink;
        
        @FindBy(xpath="//a[5][contains(@href,'/deals')]")
        WebElement dealslink;
        
        //Initializing Page Object
        public HomePage() {
            
            PageFactory.initElements(driver, this);
            
        }
        

        
        //Actions
        public String validateHomePage() {

        return driver.getTitle();
            
        }
        
        
        public boolean validateHomePageDisplayed() {
            return Homepage.isDisplayed();
        }
        
        public String validateUser() {
            
            return username.getText();
        }
        
        public boolean verifyUsername() {
            return username.isDisplayed();
        }
        
        
        
        public ContactPage clickContactLink() {         
            contactlink.click();
            return new ContactPage();
        }
        
        public DealsPage clickDeals() {
            dealslink.click();
            return new DealsPage();
        }
    }



Test Case Class
package com.crm.qa.TestCases;

import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

import com.qa.base.TestBase;
import com.qa.pages.ContactPage;
import com.qa.pages.HomePage;
import com.qa.pages.loginPage;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.ExpectedCondition;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.Assert;

public class HomePageTest extends TestBase {
    
    loginPage loginpage;
    HomePage homepage;
    ContactPage contactpage;
    
    //Create a constructor  of  HomePageTest and call the super class i.e the TestBase class constructor will be called
    public HomePageTest()  {
        
        super();
    }
    
    
    // test case should be separated - independent with each other
    // before each test cases - launch the browser and login
    // after each test cases - close the browser
    
    @BeforeMethod
    
    public void setUp() {
        
        initializtion();
        loginpage = new loginPage();
        //Login method is returning homepage object
        homepage = loginpage.login(prop.getProperty("username"), prop.getProperty("password"));
    }
    
    @Test
    public void verifyHomePageTitleTest() {
        
    String homepageTitle = homepage.validateHomePage();
    System.out.println("Print HomePage Title:::::::::::::::::" +homepageTitle);
    Assert.assertEquals(homepageTitle, "Cogmento CRM","Homepage title is not matching");
        
    }
    
    @Test 
    public void verifyUsernameTest() {
        Assert.assertTrue(homepage.verifyUsername(), "Username is not matching");
        
    }
    
    @Test
    public void verifyUserTest() {
        String Username = homepage.validateUser();
        Assert.assertEquals(Username, "Gokul Kuppusamy","Username text is not matching");
    }
    
    @Test
    public void verifyContactPageTest() {
        System.out.println("Clicking Contact Page");

        contactpage = homepage.clickContactLink();
                
    }
    
    @AfterMethod
    
    public void tearDown() {
        driver.quit();
    }

}

package com.crm.qa.TestCases;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.testng.Assert;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

import com.qa.base.TestBase;
import com.qa.pages.ContactPage;
import com.qa.pages.HomePage;
import com.qa.pages.loginPage;

public class ContactPageTest extends TestBase {

    loginPage loginpage;
    HomePage homepage;
    ContactPage contactpage;

    public ContactPageTest() {

        super();
    }

    @BeforeMethod

    public void setUp() throws Exception {
        initializtion();
        loginpage = new loginPage();
        // Login method is returning homepage object
        homepage = loginpage.login(prop.getProperty("username"), prop.getProperty("password"));
        driver.manage().timeouts().implicitlyWait(5000, TimeUnit.SECONDS);
        Thread.sleep(3000);
        homepage.validateHomePageDisplayed();
        /*
         * Thread.sleep(3000); homepage.clickContactLink(null);
         */

    }

    @Test
    public void verifyContactsPageNewButtonTest() {
    
        Assert.assertTrue(contactpage.verifyNewButton());
    }

    @Test(priority = 1)
    public void verifyContactsPageLableTest() {
        driver.manage().timeouts().implicitlyWait(5000, TimeUnit.SECONDS);
        Assert.assertTrue(contactpage.verifyContactlable(), "Contacts is missing on the page");

    }

    @Test(priority = 2)
    public void selectContactDetailsTest() {
        contactpage.selectContactDetails();
    }

    @AfterMethod

    public void tearDown() {
        driver.quit();
    }

}

java.lang.NullPointerException
    at com.crm.qa.TestCases.ContactPageTest.verifyContactsPageNewButtonTest(ContactPageTest.java:49)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)

Answer 1

请确认您是否为所有页面仅使用一个驱动程序实例，基本为此发生空点异常，解决方案使用全局变量作为驱动程序实例

公共静态 Webdriver 驱动程序；

Answer 2

initializtion();
        loginpage = new loginPage();

//below line is missing please add in HomePageTest class 
       **homepage=new Homepage();**