并行执行功能文件导致空指针异常打印在控制台上

Question

我曾尝试编写特征文件的黄瓜并行执行代码，但在控制台上打印出这样的错误：

[TestNG-PoolService-0] ERROR com.nicholas.StepsDef.ExportProduct - java.lang.NullPointerException

Element info: {Using=xpath, value=//a[@class='log-wrapper']/child::img}
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at org.openqa.selenium.remote.http.W3CHttpResponseCodec.createException(W3CHttpResponseCodec.java:187)
    at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:122)
    at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:49)
    at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:158)
    at org.openqa.selenium.remote.service.DriverCommandExecutor.execute(DriverCommandExecutor.java:83)
    at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:552)
    at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:323)
    at org.openqa.selenium.remote.RemoteWebDriver.findElementByXPath(RemoteWebDriver.java:428)
    at org.openqa.selenium.By$ByXPath.findElement(By.java:353)
    at org.openqa.selenium.remote.RemoteWebDriver.findElement(RemoteWebDriver.java:315)
    at org.openqa.selenium.support.ui.ExpectedConditions.apply(ExpectedConditions.java:205)
    at org.openqa.selenium.support.ui.ExpectedConditions.apply(ExpectedConditions.java:201)
    at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:249)
    at com.nicholas.StepsDef.AddProduct.navigateToManageProduct(AddProduct.java:65)
    at ✽.navigate to manage product(file:///C:/Users/nicholaswkc/IdeaProjects/cucumber-java-skeleton/src/test/resources/Features/AddProduct.feature:7)

05:38:22.730 [TestNG-PoolService-0] ERROR com.nicholas.StepsDef.ExportProduct - java.lang.NullPointerException
05:38:22.780 [TestNG-PoolService-0] ERROR com.nicholas.StepsDef.AddProduct - org.openqa.selenium.NoSuchSessionException: invalid session id

AddProductPageObject.java

public By lazadaLogo = By.xpath("//a[@class='log-wrapper']/child::img");

AddProduct.java

public class AddProduct {

    private AddProductPageObject page;
    private ChromeDriver driver;
    private Logger log = LogManager.getLogger(AddProduct.class);
    // ======================================================================
    public AddProduct() {
    }

    @Given("Launch the homepage and login")
    public void launchTheHomepageAndLogin() {
        log.info("Start Login");
        try {
            WebDriverManager.chromedriver().setup();
            driver =  new ChromeDriver();
            WebDriverWait timeWait = new WebDriverWait(driver, 30);
            page = PageFactory.initElements(driver, AddProductPageObject.class);
            driver.navigate().to("https://sellercenter.lazada.com.my/apps/seller/login");
            timeWait.until(ExpectedConditions.visibilityOfElementLocated(page.getLazadaSellerLogo()));

            // Input username
            driver.findElement(page.getUsername()).click();
            driver.findElement(page.getUsername()).clear();
            driver.findElement(page.getUsername()).sendKeys("nicholaswkc34@gmail.com");

            // Input password
            driver.findElement(page.getPassword()).click();
            driver.findElement(page.getPassword()).clear();
            driver.findElement(page.getPassword()).sendKeys("wlx_+279295");

            // Click submit btn
            driver.findElement(page.getSignInButton()).click();

            //assertThat(page.getPageTitle()).isEqualto("");

            Wait wait = new Wait();
            wait.implicitWait(driver, 5);

        } catch (Exception e) {
            log.error(e);
        }
    }

    @Given("navigate to manage product")
    public void navigateToManageProduct() {
        WebDriverWait waitProductLink = new WebDriverWait(driver, 30);
        waitProductLink.until(ExpectedConditions.visibilityOfElementLocated(page.getLazadaLogo()));
        driver.findElement(page.getProductLink()).click();

        WebDriverWait waitManagedProductLink = new WebDriverWait(driver, 30);
        waitManagedProductLink.until(ExpectedConditions.visibilityOfElementLocated(page.getManageProductLink()));
        driver.findElement(page.getManageProductLink()).click();
    }

此外，当我运行使用 mvn 命令时，它弹出 org.testng.xml.XmlSuite.setParallel(Ljava/lang/String;) 在此 group

上突出显示

问题：

导致错误的原因是什么？
何时应该修复 maven surefire 插件错误？

Answer 1

我看到在“com.nicholas.StepsDef.AddProduct.navigateToManageProduct(AddProduct.java:65)”处发生错误，方法 - page.getLazadaLogo()。

我假设驱动程序对象在创建 WebDriverWait waitProductLink = new WebDriverWait(driver, 30); 对象时为 null。通常，WebDriverWait 在其构造函数参数中接受 null，但是当我们尝试使用使用 null 创建的等待对象时，它会在运行时抛出错误。

解决方案：

检查步骤 'navigate to manage product' 实现中包含的驱动程序。特定于该特定块的“启动主页和登录”驱动程序分配的范围。要解决此问题，请将驱动程序变量设为静态，并在步骤“启动主页和登录”实施中为其分配驱动程序对象引用。
如果这两个步骤运行并行，那么您还需要在步骤“导航到管理产品”实现中创建驱动程序对象。

Answer 2

通过将初始化代码移动到@Before 方法来解决它。

并行执行功能文件导致空指针异常打印在控制台上

Parallel execution of features file causes null pointer exception printer out on console

java

cucumber

cucumber-java