java.lang.NullPointerException 尝试将页面对象与 Appium 和 TestNG 一起使用

Question

我正在尝试使用 Browserstack 使用 Appium 和 TestNG 编写基本测试。我正在尝试添加页面对象，但是当我尝试构造页面对象时，我不断收到空指针异常。

配置：

public class BrowserStackConfig {
    protected AppiumDriver<MobileElement> appiumDriver;

    @BeforeMethod(alwaysRun = true)
    @Parameters("platform")
    public void setUp(String platform, ITestResult testMethod) throws Exception {
        Map<String, Object> config = readConfigFromFile();
        DesiredCapabilities capabilities = new DesiredCapabilities();
        ConfigReader reader = new ConfigReader();

        String device;
        String os;
        String app;

        switch (platform) {
            case "android":
                app = (String) config.get("androidApp");
                device = (String) config.get("androidDevice");
                os = (String) config.get("androidVersion");
                break;
            case "ios":
                device = (String) config.get("iOSDevice");
                os = (String) config.get("iOSVersion");
                app = (String) config.get("iosApp");
                break;
            default:
                throw new IllegalArgumentException("Unsupported OS: " + platform);
        }

        capabilities.setCapability("device", device);
        capabilities.setCapability("os_version", os);
        capabilities.setCapability("platformName", platform);
        capabilities.setCapability("app", app);
        capabilities.setCapability(MobileCapabilityType.NEW_COMMAND_TIMEOUT, 60);
        capabilities.setCapability("idleTimeout", "1000");
        capabilities.setCapability("settings[enableMultiWindows]", true);

        String url = reader.urlBrowserStack(testMethod);

        if ("android".equals(platform)) {
            appiumDriver = new AppiumDriver<>(new URL(url), capabilities);
        } else {
            appiumDriver = new IOSDriver<>(new URL(url), capabilities);
        }
    }

    private Map<String, Object> readConfigFromFile() throws IOException {
        Yaml yaml = new Yaml();
        try (FileReader fileReader = new FileReader("browserstack.yml")) {
            return yaml.load(fileReader);
        }
    }

    @AfterMethod(alwaysRun = true)
    public void tearDown(ITestResult testResult) throws Exception {
        ResultsListener result = new ResultsListener(appiumDriver);
        if (ITestResult.SUCCESS == testResult.getStatus()) {
            result.passResult(appiumDriver);
            Thread.sleep(3000);
        } else {
            result.failResult(appiumDriver);
            Thread.sleep(3000);
        }
        appiumDriver.quit();
    }
}

基本页面：

public class BasePage extends BrowserStackConfig{

    protected AppiumDriver<MobileElement> appiumDriver; 

    public BasePage (AppiumDriver<MobileElement> appiumDriver) {
        appiumDriver = this.appiumDriver;
    }
    
}

登陆页面：

public class LandingPage extends BasePage {

    public LandingPage(AppiumDriver<MobileElement> appiumDriver) {
        super(appiumDriver);
    }

    // Element locators
    private AndroidElement  logInBtn = (AndroidElement ) new WebDriverWait(appiumDriver, 10).until(
        ExpectedConditions.visibilityOfElementLocated(MobileBy.id(
            "button_log_in"
        ))
    );

    // Methods
    public boolean isInitialized() {
        try {
            return logInBtn.isDisplayed();
        } catch (Exception e) {
            return false;
        }
    }
}

和应用测试

public class AppTest extends BrowserStackConfig {

    private final SoftAssert assertion = new SoftAssert();

    @Test
    public void test() throws Exception {
        LandingPage landingPage = new LandingPage(appiumDriver);

        // assert landing page is loaded
        assertion.assertTrue(landingPage.isInitialized());
    }
}

当我运行测试时，我得到

AppTest.test » NullPointer

对应线路

LandingPage landingPage = new LandingPage(appiumDriver);

我已经尝试了所有能找到的初始化和构建页面对象的组合，但每当我尝试构建页面时，我总是收到 NPE。

Answer 1

弄清楚了，为后代发布答案

一个重要的词：

protected

变量

appiumDriver

在BrowserStackConfig中受到保护，因此当我尝试将其传递到landingPage以创建页面对象时，它接收到null。将第一行更改为

public AppiumDriver<MobileElement> appiumDriver;

解决了问题。

（此外，BasePage 不应该扩展 BrowserStackConfig）