Appium, Java & Testng - 找到 NullPointerException 的原因

Question

我在 Appium 和模拟器启动之前收到 NullPointerException。因此，尝试通过代码中的 sysout 行进行调试根本没有帮助。如果有人有什么建议，请发送给我，因为我快要疯了！

我的依赖项：

<dependencies>

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.9</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>

        <dependency>
            <groupId>io.appium</groupId>
            <artifactId>java-client</artifactId>
            <version>7.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>7.0.0-beta3</version>
        </dependency>

        <dependency>
            <groupId>com.googlecode.json-simple</groupId>
            <artifactId>json-simple</artifactId>
            <version>1.1.1</version>
        </dependency>
        <dependency>
            <groupId>io.rest-assured</groupId>
            <artifactId>rest-assured</artifactId>
            <version>4.0.0</version>
        </dependency>

        <dependency>
            <groupId>io.cucumber</groupId>
            <artifactId>cucumber-testng</artifactId>
            <version>4.0.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.cucumber</groupId>
            <artifactId>cucumber-java</artifactId>
            <version>4.0.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.cucumber</groupId>
            <artifactId>cucumber-core</artifactId>
            <version>4.0.0</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

我的 Hooks class：

package MA.test;

import io.appium.java_client.AppiumDriver;
import io.appium.java_client.MobileElement;
import io.appium.java_client.android.AndroidDriver;
import io.appium.java_client.remote.AndroidMobileCapabilityType;
import io.appium.java_client.remote.MobileCapabilityType;
import io.appium.java_client.service.local.AppiumDriverLocalService;
import io.appium.java_client.service.local.AppiumServiceBuilder;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Parameters;

import java.net.MalformedURLException;
import java.net.URL;

public class Hooks {

    public AppiumDriver driver;
    public AppiumDriverLocalService service;

    @Parameters({"platformVersion", "emulatorNumber", "deviceName", "port"})
    @BeforeTest(alwaysRun = true)
    public void startAppiumServer(String platformVersion, String emulatorNumber, String deviceName, String port) throws InterruptedException, MalformedURLException {
        System.out.println("\n ABC");
        service = new AppiumServiceBuilder()
                .usingPort(Integer.valueOf(port))
                .build();
        service.start();
        DesiredCapabilities caps = new DesiredCapabilities();
        caps.setCapability(MobileCapabilityType.PLATFORM_VERSION, platformVersion);
        caps.setCapability(MobileCapabilityType.DEVICE_NAME, emulatorNumber);
        caps.setCapability(AndroidMobileCapabilityType.AVD, deviceName);
        caps.setCapability(MobileCapabilityType.PLATFORM_NAME, "Android");
        caps.setCapability(MobileCapabilityType.APPLICATION_NAME, "Name");
        caps.setCapability(MobileCapabilityType.APPIUM_VERSION, "1.14.0");
        caps.setCapability(AndroidMobileCapabilityType.APP_ACTIVITY, "activity");
        caps.setCapability(AndroidMobileCapabilityType.APP_PACKAGE, "package");
        caps.setCapability(MobileCapabilityType.AUTOMATION_NAME, "UiAutomator2");

        driver = new AndroidDriver<MobileElement>(new URL("http://0.0.0.0:" + port + "/wd/hub"), caps);

        System.out.println("\n Appium server: " + service.getUrl());
        Thread.sleep(2000);
    }

    @AfterTest
    public void teardown() {
        service.stop();
        driver.quit();
        driver.closeApp();
        System.out.println("\n Test quit");
    }
}

我的 TestRunner class：

package MA.steps;

import cucumber.api.CucumberOptions;
import cucumber.api.testng.AbstractTestNGCucumberTests;

@CucumberOptions(
        plugin = {"pretty", "html:target/cucumber-reports"}
        , monochrome = true
        , features = "src/test/java/feature"
        , tags = "@Login"
)

public class TestRunner extends AbstractTestNGCucumberTests {

}

我的 testng.xml 文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "http://testng.org/testng-1.0.dtd">
<suite name="Android Parallel Execution" parallel="tests" thread-count="2" verbose="7">
    <test name="Device1">
        <parameter name="platformVersion" value="9.0"/>
        <parameter name="emulatorNumber" value="emulator-5554"/>
        <parameter name="deviceName" value="Android9_Nexus"/>
        <parameter name="port" value="4723"/>
        <classes>
            <class name="MA.steps.TestRunner"/>
        </classes>
    </test>
</suite>

我收到以下错误：

java.lang.NullPointerException at screens.myAccountOverviewScreen.logoutAccount(myAccountOverviewScreen.java:104)

它指向以下代码行：

driver.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);

这是第一次在我的测试中调用 driver，但令我困惑的是它甚至没有启动 appium 或启动模拟器就抛出 nullpointerexception。

Answer 1

问题出在你的测试代码上

您创建了套件 xml 文件以仅包含您的 TestRunner class。但是整个 appium 实例化逻辑都卡在 Hooks class 中，它通过 TestNG 配置注释 @BeforeTest 和 @AfterTest 来完成。但是这个 class 既不包含在您的套件中，也不包含您的测试 class (TestRunner) 扩展它。因此，您的配置不会被调用，从而导致 AppiumDriver 对象的空值。

要解决此问题，您可以执行以下操作之一：

编辑您的套件 xml 文件并在其中包含 Hooks class。 (或)
构建一个实现 IInvokedMethodListener 的 TestNG 侦听器并将您的驱动程序实例化到其 beforeInvocation

Appium, Java & Testng - 找到 NullPointerException 的原因

Appium, Java & Testng - find the reason for a NullPointerException

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