在PageFactory（Selenium + Java）中获取NPE NullPointerException

Question

我正在尝试为我的测试框架实现Page Factory模式，但是在尝试访问元素或与元素进行交互时却得到了NPE。顺便说一句，我正在使用Spring Dependency Injection在测试之间（而不是构造函数）共享WebDriver实例，因此我在非静态块内实现了PageFactory initElements()以能够到达它。顺便说一句，没有PageFactory（没有@FindBy且没有带评论的项），它可以完美地工作。这是我的PO.class代码：

@Component
public class HomePage extends BasePage {
  @Autowired
  private DatabasesPage databasesPage;
  @Autowired
  private UserAccountsPage userAccountsPage;

  public static Logger log = LogManager.getLogger(HomePage.class.getName());
  private String themeLabelColorHex = "#235a81";
  private Select themeList;

 /* private By databasesHeaderButton = By.cssSelector("#topmenu > li:nth-child(1)"),
             userAccountsHeaderButton = By.cssSelector("#topmenu > li:nth-child(4)"),
             languagesDropdown = By.id("sel-lang"),
             themeDropdown = By.name("set_theme"),
             themeLabel = By.xpath("//*[@id='li_select_theme']//a");*/

  @FindBy(how = How.CSS, css = "#topmenu > li:nth-child(1)")  private WebElement databasesHeaderButton;
  @FindBy(how = How.CSS, css = "#topmenu > li:nth-child(4)")  private WebElement userAccountsHeaderButton;
  @FindBy(how = How.ID, id = "sel-lang") private WebElement languagesDropdown;
  @FindBy(how = How.NAME, name = "set_theme") private WebElement themeDropdown;
  @FindBy(how = How.XPATH, xpath = "//*[@id='li_select_theme']//a") private WebElement themeLabel;

  {
    PageFactory.initElements(driver,this);
    System.out.println("**************** THIS IS A NON-STATIC FIELD REACHED BY DEP INJ ****************");
  }

  public HomePage openUp() {
    String propertiesPath = get(System.getProperty("user.dir"),
      "src", "main", "java", "base", "configuration", "config.properties").normalize().toString();

    try {
      Properties properties = new Properties();
      properties.load(new FileInputStream(propertiesPath));
      String url = properties.getProperty("url");

      driver.get(url);
    }
    catch ( IOException e) {
      log.error("Properties file is not found");
      log.error("\n " + ExceptionUtils.getStackTrace(e));
    }

    return this;
  }

  public DatabasesPage goToDatabasesPage() {
    databasesHeaderButton.click();
    return databasesPage;
  }

  public UserAccountsPage goToUserAccountsPage() {
    userAccountsHeaderButton.click();
    return userAccountsPage;
  }

  public HomePage changeLanguage(String langValue) {
    try {
      Select langList = new Select(languagesDropdown);
      String currentLang = langList.getFirstSelectedOption().getAttribute("value");
      if (langValue.equalsIgnoreCase(currentLang)) log.warn("Desired language is already selected!");
      else langList.selectByValue(langValue);
    }
    catch (Exception e) {
      log.error("\n" + ExceptionUtils.getStackTrace(e));
    }

    return this;
  }

  public HomePage changeTheme(String themeValue) {
    try {
      themeList = new Select(themeDropdown);
      String currentTheme = themeList.getFirstSelectedOption().getAttribute("value");

      if (themeValue.equalsIgnoreCase(currentTheme))
        log.warn("Desired theme is already selected!");
      else {
        themeList.selectByValue(themeValue);
        driver.navigate().refresh();
        themeLabelColorHex = "#0000ff";
      }
    }
    catch (Exception e) {
      log.error("\n" + ExceptionUtils.getStackTrace(e));
    }

    return this;
  }

  public HomePage setDefaultTheme() {
    themeList = new Select(themeDropdown);
    themeList.selectByValue("pmahomme");
    themeLabelColorHex = "#235a81";
    return this;
  }

  public boolean isLanguageChanged() {
    return true; // TO DO
  }

  public boolean isThemeChanged() {
    String RGBColor = themeLabel.getCssValue("color"); // I'm getting NPE here somehow
    String HexColor = Color.fromString(RGBColor).asHex();

    return HexColor.equalsIgnoreCase(themeLabelColorHex);
  }

}

这是我的测试方法：

@Test
  @Description("Change website theme")
  public void changeWebsiteTheme() {
    homePage.openUp().changeTheme("original");
    assertThat(true).isEqualTo(homePage.isThemeChanged()); // and it fails here but it didn't perform previous step - changeTheme();

    homePage.setDefaultTheme();
    assertThat(true).isEqualTo(homePage.isThemeChanged());
  }

enter code here

Answer 1

要启动用构造函数编写的PageFactory，必须通过创建类的对象来启动它。this帮助我实现了这一目标。