How does a constructor work in a TestNG class inheriting from a parent java class

Question

In testng class, I have a constructor with following methods super(driver) - this calls parent class and passes driver object setup() - this call goes to parent class,where a new driver object is created

Eg code

public class LoginTestNG extends ProjectTestBase {

  WebDriver driver;  
  static By locator = By.name("airline");



  public LoginTestNG(WebDriver driver) {
      super(driver);
      System.out.println("I am in constructor");
      setup();

  }  



  @Test(dataProvider = "logn")
  public static void login_with_valid_user_param(String uname, String passwd){  
      LoginActions.submit_login(uname,passwd);      
  }

  @DataProvider(name = "logn")
  public static Object[][] loginData(){

      return new Object[][]{{"test","test"}};
  }

}

Parent class code:

public class ProjectTestBase{

  public LoginActions loginActions;
    static LoginPage loginPage;
    public static WebDriver driver;
    public ProjectTestBase(WebDriver driver){               
        this.driver=driver;     
    }


  public static void setup(){
      driver = startBrowser("firefox");
      createActions(driver);
      createPages(driver);
      launchURL("http://newtours.demoaut.com/index.php");
      driver.manage().window().maximize();
  }

  public static void createActions(WebDriver driver){
      loginActions = new com.newtours.actions.LoginActions(driver);
  }

  public static void createPages(WebDriver driver){
      loginPage = new LoginPage(driver);
  }
}

my question is: 1. This code works fine if i run the test in a java class 2. If I add the test to a testNG class it does not work, I mean, I am getting
null pointer exception because driver object is null. I think the constructor is not getting invoked, I need help to understand if the constructor works differently in a testng class.

Thanks sk

Answer 1

TestNG doesn't call your constructor with parameter WebDriver driver so it's null.

If you want to pass some arguments to your test you can use:

• @Parameters http://testng.org/doc/documentation-main.html#parameters
• @DataProvider http://testng.org/doc/documentation-main.html#parameters-dataproviders

Or you can init your WebDriver in @BeforeSuite / @BeforeClass etc. methods.