Flutter自动化元素定位方法调用报错问题排查

问题背景 #

原本为Android App实现了一套元素定位逻辑，现在复刻到Flutter App后调用findMobileLocatorElement报错，需排查方法实现或调用过程中的问题。

Android原定位代码 #

public static AppiumLocator findMobileLocatorElement(
      final String pageName,
      final String elementName,
      AppiumDriver driver,
      Object... dynamicLocatorValue) {
    return findMobileLocatorElement(
        pageName, elementName, driver, AppiumLocator::getElement, dynamicLocatorValue);
  }

  /**
   * Finds the page element.
   *
   * @param pageName page name tag in web locator file.
   * @param elementName name of element.
   * @return instance of weblocator class.
   */
  private static AppiumLocator findMobileLocatorElement(
      final String pageName,
      final String elementName,
      AppiumDriver webdriver,
      BiFunction<String, String, AppiumLocator> appiumLocatorProvider,
      Object... dynamicLocatorValue) {
    AppiumLocator appiumLocator;
    Map<String, String> locatorMap = new HashMap<>();
    try {
      locatorMap = WebLocatorFileTypeFactory.getInstance().getLocatorValue(pageName, elementName);
    } catch (JAXBException exception) {
      log.warn("Failed to read OR file for pagename {}", pageName, exception);
    }
    if (!locatorMap.isEmpty()) {
      for (final Map.Entry<String, String> entry : locatorMap.entrySet()) {
        if (0 == dynamicLocatorValue.length) {
          appiumLocator = appiumLocatorProvider.apply(entry.getValue(), entry.getKey());
        } else {
          appiumLocator =
              appiumLocatorProvider.apply(
                  String.format(entry.getValue(), dynamicLocatorValue), entry.getKey());
        }
        try {
          webdriver.findElement(appiumLocator.getBy());
          return appiumLocator;
        } catch (NoSuchElementException e) {
          log.info("Not able to find element: {} with locator : {}.", elementName, appiumLocator);
        }
      }
    } else {
      log.error(
          "NameOfElement or SectionName is given wrong in object repository file or PageName in Page Object"
              + " Class is wrong");
    }
    webdriver.manage().timeouts().implicitlyWait(Duration.ofSeconds(20));
    throw new NoSuchElementException(
        String.format(
            "no valid WebLocator found in object repository for page: %s and element: %s",
            pageName, elementName));
  }

Flutter复刻的定位代码 #

public static FlutterLocator findMobileLocatorElement(
          final String pageName,
          final String elementName,
          AppiumDriver driver,
          Object... dynamicLocatorValue) {
    return findMobileLocatorElement(
            pageName, elementName, driver, FlutterLocator::getElement, dynamicLocatorValue);
  }


  private static FlutterLocator findMobileLocatorElement(
          final String pageName,
          final String elementName,
          AppiumDriver webdriver,
          BiFunction<String, String, FlutterLocator> appiumLocatorProvider,
          Object... dynamicLocatorValue) {
    FlutterLocator flutterLocator = null;
    Map<String, String> locatorMap = new HashMap<>();
    try {
      locatorMap = WebLocatorFileTypeFactory.getInstance().getLocatorValue(pageName, elementName);
    } catch (JAXBException exception) {
      log.warn("Failed to read OR file for pagename {}", pageName, exception);
    }
    if (!locatorMap.isEmpty()) {
      for (final Map.Entry<String, String> entry : locatorMap.entrySet()) {
        if (0 == dynamicLocatorValue.length) {
          flutterLocator = appiumLocatorProvider.apply(entry.getValue(), entry.getKey());
        } else {
          flutterLocator =
                  appiumLocatorProvider.apply(
                          String.format(entry.getValue(), dynamicLocatorValue), entry.getKey());
        }
        try {
          webdriver.findElement(flutterLocator.getBy());
          return flutterLocator;
        } catch (NoSuchElementException e) {
          log.info("Not able to find element: {} with locator : {}.", elementName, flutterLocator);
        }
      }
    } else {
      log.error(
              "NameOfElement or SectionName is given wrong in object repository file or PageName in Page Object"
                      + " Class is wrong");
    }
    webdriver.manage().timeouts().implicitlyWait(Duration.ofSeconds(20));
    throw new NoSuchElementException(
            String.format(
                    "no valid WebLocator found in object repository for page: %s and element: %s",
                    pageName, elementName));
  }

排查出的问题点 #

• FlutterLocator.getElement方法未适配Flutter专属定位策略：Android的定位策略（如id、xpath）不适用于Flutter App，Flutter需要使用flutterByText、flutterBySemanticsLabel等专属定位方式，如果FlutterLocator的getElement方法未实现这些策略的解析，会直接导致定位失败。
• 定位对象库（OR）内容不匹配：若复用了Android的对象库，其中存储的是原生Android定位键值对，无法被Flutter解析；即使新建了Flutter定位项，若格式不符合FlutterLocator的要求，locatorMap中的内容也无法生成有效定位器。
• getBy()返回类型错误：Appium定位Flutter元素需要使用FlutterBy相关实现类，而非原生Android的By类。如果FlutterLocator.getBy()返回原生By实例，调用webdriver.findElement()时会因类型不兼容抛出异常。
• 空指针风险：flutterLocator初始化为null，若locatorMap为空或所有定位尝试失败，在catch块打印日志时会触发空指针异常，而Android版本中AppiumLocator在循环内必然被赋值，不存在此问题。
• 隐式等待设置时机无效：在所有定位尝试失败后才设置隐式等待，此时已经要抛出异常，完全起不到辅助定位的作用，正确的做法是在driver初始化时或查找元素前设置。
• 异常信息误导：抛出的异常文本写的是no valid WebLocator found，但实际针对的是FlutterLocator，会干扰问题排查，需修改提示文本。

内容的提问来源于stack exchange，提问作者Bhagyashree meena