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使用TestNg和Maven的Selenium WebDriver中的NullPointerException

testng nullpointerexception selenium-webdriver maven eclipse

J91 · 技术社区 · 6 年前

我目前正在构建一个Maven项目,该项目还包括Eclipse中的TestNg库。我正在使用最新的Selenium版本3.8.1运行Java 8(我听说这导致了其他人的问题,所以从Java 9切换过来)。我的项目工作顺利,没有任何问题,测试运行得很好,然后开始抛出 NullPointerException s、我再次尝试建造这个项目,但没有成功。

这是我的设置:

下面是我使用的TestBase类 @BeforeSuite 和 @AfterSuite 实例化WebDriver。这将毫无问题地启动。

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Properties;

import org.apache.log4j.Logger;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.testng.annotations.AfterSuite;
import org.testng.annotations.BeforeSuite;

public class TestBaseMaven {

    public WebDriver driver;
    public static FileInputStream fis;
    public static FileInputStream fis1;
    public static Properties config = new Properties();
    public static Properties OR = new Properties();
    public static Logger log;

    @BeforeSuite
    public void setUp() throws IOException, InterruptedException {
        fis = new FileInputStream("C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2\\src\\test\\resources\\properties\\Config.properties");
        config.load(fis);
        fis1 = new FileInputStream("C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2\\src\\test\\resources\\properties\\OR.properties");
        OR.load(fis1);

        if(driver==null) {
            if(config.getProperty("browser").equals("chrome")) {
                System.setProperty("webdriver.chrome.driver", "C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2\\src\\test\\resources\\executables\\chromedriver.exe");
                driver = new ChromeDriver();
            } else if(config.getProperty("browser").equals("firefox")) {
                System.setProperty("webdriver.gecko.driver", "C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2\\src\\test\\resources\\executables\\geckodriver.exe");
                DesiredCapabilities dc = DesiredCapabilities.firefox();
                dc.setCapability("marionette", true);
                driver=new FirefoxDriver();
            } else if(config.getProperty("browser").equals("ie")) {
                System.setProperty("webdriver.ie.driver", "C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2\\src\\test\\resources\\executables\\IEDriverServer.exe");
                driver = new InternetExplorerDriver();
            }
        }

        driver.get(config.getProperty("testUrl"));
        driver.manage().window().maximize();
        Thread.sleep(2000);
    }

    public boolean isElementPresent(By by) {
        try {
            driver.findElement(by);
            return true;
        } catch(Throwable t) {
            return false;
        }
    }

    @AfterSuite
    public void tearDown() {
        if(driver!=null) {
            driver.quit();
        }
    }
}

这是我的第一次测试,它也运行良好,正在通过。虽然有时这也会引发 空指针异常 我使用的位置 Webdriver ,例如在中 driver.findElement ...

import org.openqa.selenium.By;
import org.testng.Assert;
import org.testng.annotations.Test;

import com.kohout.base.TestBaseMaven;

public class ManagerLoginTest extends TestBaseMaven {

    @Test
    public void managerLoginTest() throws InterruptedException {
        driver.findElement(By.cssSelector(config.getProperty("managerLogin"))).click();
        Thread.sleep(2000);
        Assert.assertTrue(isElementPresent(By.cssSelector(OR.getProperty("addCust"))));
    }

}

这是我的第二次测试。不管什么原因,这个总是 空指针异常 每当我使用实例化的驱动程序变量(在 @BeforeSuite之前 ).

import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;
import org.testng.annotations.Test;

import com.kohout.base.TestBaseMaven;

public class AddCustomerTest extends TestBaseMaven {

    @Test
    public void addCustomerTest() {
         driver.findElement(By.xpath("/html/body/div[3]/div/div[2]/div/div[1]/button[1]"));
    }

}

这是我的堆栈跟踪:

java.lang.NullPointerException
at com.kohout.testcases.AddCustomerTest.addCustomerTest(AddCustomerTest.java:14)
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)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:124)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:571)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:707)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:979)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:125)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:109)
at org.testng.TestRunner.privateRun(TestRunner.java:648)
at org.testng.TestRunner.run(TestRunner.java:505)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:455)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:450)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:415)
at org.testng.SuiteRunner.run(SuiteRunner.java:364)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:84)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1187)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1116)
at org.testng.TestNG.runSuites(TestNG.java:1028)
at org.testng.TestNG.run(TestNG.java:996)
at org.testng.remote.AbstractRemoteTestNG.run(AbstractRemoteTestNG.java:114)
at org.testng.remote.RemoteTestNG.initAndRun(RemoteTestNG.java:251)
at org.testng.remote.RemoteTestNG.main(RemoteTestNG.java:77)

我还想包括我的testng。xml,我也在pom中调用它。xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Bank Suite">     
  <test name="Login Test">
    <classes>
      <class name="com.kohout.testcases.ManagerLoginTest"/>
      <class name="com.kohout.testcases.AddCustomerTest"/>
    </classes>     
  </test> <!-- Test -->    
</suite> <!-- Suite -->

这是我的POM。xml也是:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.kohout</groupId>
    <artifactId>MavenProject2</artifactId>
    <version>0.0.1-SNAPSHOT</version>


    <dependencies>        
        <!-- https://mvnrepository.com/artifact/org.seleniumhq.selenium/selenium-java -->
        <dependency>
            <groupId>org.seleniumhq.selenium</groupId>
            <artifactId>selenium-java</artifactId>
            <version>3.8.1</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.testng/testng -->
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>6.13.1</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml-schemas -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml-schemas</artifactId>
            <version>3.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.xmlbeans/xmlbeans -->
        <dependency>
            <groupId>org.apache.xmlbeans</groupId>
            <artifactId>xmlbeans</artifactId>
            <version>2.6.0</version>
        </dependency>

    </dependencies>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.20.1</version>
                    <configuration>
                        <suiteXmlFiles>
                            <suitXmlFile>C:\Users\Kohout\eclipse-workspace\MavenProjects\MavenProject2\testng.xml</suitXmlFile>
                        </suiteXmlFiles>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>

</project>

谢谢你的时间和帮助。

1 回复 | 直到 6 年前

Krishnan Mahadevan 6 年前

问题出在测试代码中。您正在使用 @BeforeSuite 基类中的注释来初始化 WebDriver 例子

TestNG执行 @BeforeSuite之前 每个仅一次带注释的方法 <suite> 标签两个测试类都有相同的基类,因此初始化方法 setUp() 仅为测试类调用 com.kohout.testcases.ManagerLoginTest 而且不会被要求 com.kohout.testcases.AddCustomerTest .

请将其更改为开始使用 @BeforeClass (或) @BeforeMethod 如果测试类只有一个注释 @Test 方法

如果您的测试类有多个 @测试 方法,那么您基本上应该使用 ThreadLocal 变体(或)您应该使用TestNG侦听器初始化webdriver,然后查询webdriver实例。

你可以参考我的博客帖子 here 了解如何使用TestNG侦听器以促进并行执行。

下面的示例显示了线程本地变量的外观

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.ie.InternetExplorerDriver;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
import java.util.logging.Logger;

public class TestBaseMavenRefactored {

    private static final String PREFIX = "C:\\Users\\Kohout\\eclipse-workspace\\MavenProjects\\MavenProject2";

    private static final ThreadLocal<WebDriver> driver = new ThreadLocal<>();
    private Properties config = new Properties();
    private Properties OR = new Properties();
    public static Logger log;

    protected WebDriver getDriver() {
        return driver.get();
    }

    protected Properties getConfig() {
        return config;
    }

    public Properties getOR() {
        return OR;
    }

    private void cleanupDriver() {
        driver.get().quit();
        driver.remove();
    }

    @BeforeMethod
    public void setUp() throws IOException, InterruptedException {
        FileInputStream fis = new FileInputStream(PREFIX + "\\src\\test\\resources\\properties\\Config.properties");
        config.load(fis);

        FileInputStream fis1 = new FileInputStream(PREFIX + "\\src\\test\\resources\\properties\\OR.properties");
        OR.load(fis1);

        switch (config.getProperty("browser")) {
            case "chrome":
                System.setProperty("webdriver.chrome.driver", PREFIX + "\\src\\test\\resources\\executables\\chromedriver.exe");
                driver.set(new ChromeDriver());
                break;

            case "firefox":
                System.setProperty("webdriver.gecko.driver", PREFIX + "\\src\\test\\resources\\executables\\geckodriver.exe");
                DesiredCapabilities dc = DesiredCapabilities.firefox();
                dc.setCapability("marionette", true);
                driver.set(new FirefoxDriver());
                break;

            case "ie":
                System.setProperty("webdriver.ie.driver", PREFIX + "\\src\\test\\resources\\executables\\IEDriverServer.exe");
                driver.set(new InternetExplorerDriver());
                break;
        }
        getDriver().get(config.getProperty("testUrl"));
        getDriver().manage().window().maximize();
        Thread.sleep(2000);
    }

    public boolean isElementPresent(By by) {
        try {
            getDriver().findElement(by);
            return true;
        } catch (Throwable t) {
            return false;
        }
    }

    @AfterMethod
    public void tearDown() {
        cleanupDriver();
    }
}

下面是重构测试类现在的样子:

import org.openqa.selenium.By;
import org.testng.Assert;
import org.testng.annotations.Test;

public class ManagerLoginTest extends TestBaseMavenRefactored {
    @Test
    public void managerLoginTest() throws InterruptedException {
        getDriver().findElement(By.cssSelector(getConfig().getProperty("managerLogin"))).click();
        Thread.sleep(2000);
        Assert.assertTrue(isElementPresent(By.cssSelector(getOR().getProperty("addCust"))));
    }
}