Are other classes able to access the webdriver instance when extending test base class? Getting NullPointerException Error

Question

I am getting this error when running the below selenium scripts using TestNG with Selenium Grid. I'm extending the testbase class to access the WebDriver, but I'm not sure if each class is getting the WebDriver instance correctly since I'm getting a NullPointerException?

The tests scrolls to the first item to click and doesn't click it. I'm new to Java, please advise. I am wondering if I'm understanding inheritance and initiation of objects correctly. Thanks for your help.

java.lang.NullPointerException

Answer 1

Agree with @Dale Emery.

Use this code:

public class WatchTV {

    WebDriver driver;
    WebDriverWait wait;
    int waitseconds = 60;

    public WatchTV(WebDriver driver){
        this.driver = driver;
        wait = new WebDriverWait(driver, waitseconds);
    }

    By watchtvlink = By.linkText("Watch TV »");

    public WebElement WatchTVLink()
    {
        wait.until(ExpectedConditions.elementToBeClickable(watchtvlink));
        return driver.findElement(watchtvlink);
    }

}

Answer 2

Your Setup() method runs (and initializes the driver) only in the Pg_WatchTV_Test class.

Merely extending TestBase does not cause TestNG to run your setup method. It runs setup methods (annotated by @BeforeMethod and the like) only if the class has test methods.

Your WatchTV class has no tests, so TestNG does not treat it as a test class. So the Setup() method in WatchTV never runs. So your WatchTV instance has no driver.

Rather than making WatchTV extend TestBase to get a driver:

1. Write a WatchTV constructor that takes a WebDriver parameter.
2. Do one or the other of:
   • Create the WebDriverWait instance in the constructor, using the passed driver.
   • In the constructor, save the driver to a field. Then in the WatchTVLink() method, create the WebDriverWait instance using the driver field. (See kotoj's excellent example.)