How to call a method from one class to another class when both are TestNG classes

Question

I have 2 TestNG classes which are:

1. ProductCanvas

   package objectRepo;
   
   import java.util.List;
   import org.openqa.selenium.By;
   import org.openqa.selenium.WebDriver;
   import org.openqa.selenium.WebElement;
   import org.testng.annotations.Test;
   
   public class ProductCanvas {
       private WebDriver driver;
       private By product = By.tagName("app-product-item");
       private By productName = By.xpath("//span[@itemprop='name']");
       private By addToCartButton = By.xpath("//span[contains(text(), 'Add to Cart')]");
       private By productImage = By.xpath("//img[@itemprop='image']");
       private By favIcon = By.cssSelector(".fa.fa-heart");
       private By price = By.xpath("//meta[@itemprop='price']"); 
   
       public ProductCanvas(WebDriver driver) {
           this.driver = driver;
       }
   
       public WebElement getProduct() {
           return driver.findElement(product);
       }
   
       public WebElement getProductName() {
           return driver.findElement(productName);
       }
   
       public List<WebElement> getProductNames() {
           return driver.findElements(productName);   
       }
   
       public WebElement getAddToCartButton() {
           return driver.findElement(addToCartButton);
       }
   
       public List<WebElement> getAddToCartButtons() {
           return driver.findElements(addToCartButton);   
       }
   
       public WebElement getProductImage() {
           return driver.findElement(productImage);
       }
   
       public WebElement getFavIcon() {
           return driver.findElement(favIcon);
       }
   
       public List<WebElement> getfavIcons() {
           return driver.findElements(favIcon);   
       }
   
       public WebElement getPrice() {
           return driver.findElement(price);
       }
   
       public List<WebElement> getPrices() {
           return driver.findElements(price);   
       }
   }
   

2. ProductTC

   package productTestCases;
   
   import java.util.ArrayList;
   import java.util.List;
   import java.util.concurrent.TimeUnit;
   import org.openqa.selenium.WebDriver;
   import org.openqa.selenium.WebElement;
   import org.openqa.selenium.chrome.ChromeDriver;
   import org.testng.annotations.BeforeTest;
   import org.testng.annotations.Test;
   import objectRepo.Cart;
   import objectRepo.ProductCanvas;
   
   public class ProductTC {
       private WebDriver driver;
       private String baseUrl = "http://test.com";
   
       public ProductTC(WebDriver driver) {
           this.driver = driver;
       }
   
       @BeforeTest
       public void openBrowser() {
           System.setProperty("driver.webdriver.chrome", "C://chromedriver.exe");
           driver = new ChromeDriver();
           driver.get(baseUrl);
           driver.manage().window().maximize();
           driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
       }
   
       @Test
       public void test1() {
           ProductCanvas pc = new ProductCanvas(driver);
           int count = pc.getPrices().size();
           System.out.println(count);
       }
   }
   

When I try to run ProductTC, nothing happens and this is displayed on console:

===============================================
    Default test
    Tests run: 0, Failures: 0, Skips: 0
===============================================

But when I remove the ProductTC's constructor it runs. How would I be able to run ProductTC without removing the constructor given that another class below would need to call its method?

3. LandingPageTestCases

   package productTestCases;
   
   import java.util.concurrent.TimeUnit;
   import org.openqa.selenium.WebDriver;
   import org.openqa.selenium.chrome.ChromeDriver;
   import org.testng.annotations.BeforeTest;
   import org.testng.annotations.Test;
   
   import objectRepo.Cart;
   
   public class LandingPageTestCases {
       private WebDriver driver;
       private String baseUrl = "http://test.com";
   
       public LandingPageTestCases(WebDriver driver) {
           this.driver = driver;
       }
   
       @BeforeTest
       public void openBrowser() {
           System.setProperty("driver.wedriver.chrome", "C://chromedriver.exe");
           driver = new ChromeDriver();
           driver.get(baseUrl);
           driver.manage().window().maximize();
           driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
       }
   
       @Test
       public void addProductsToCart() throws InterruptedException {
           ProductTC ptc = new ProductTC(driver);
           ptc.test1();
       }
   }
   

Answer 1

Extract the common code into a separate helper class (not a test class). Then have both test classes instantiate the helper and call its method to do the common task.

You could extract the common code into a base class, but base classes tend to become tangled or bloated as different subclasses demand different behavior from the base class.

Answer 2

My suggestion would be instead of trying to use the ProductTC class in LandingPageTestCases class.

You can just directly use the page object methods of ProductCanvas in the LandingPageTestCases class by creating its instance as you have done above:

class LandingPageTestCases {
...
@BeforeTest
...

    @Test
    public void addProductsToCart() throws InterruptedException {
      ProductCanvas pc = new ProductCanvas(driver);
      int count = pc.getPrices().size();
      System.out.println(count);
    }
}

By doing such way you would also avoid any dependency between your test cases.