DataProviders — Data-Driven Testing

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import org.testng.Assert;

public class LoginDataDrivenTest {

    @DataProvider(name = "loginData")
    public Object[][] getLoginData() {
        return new Object[][] {
            // username,    password,      shouldPass
            { "admin",      "admin123",    true  },
            { "testuser",   "password",    true  },
            { "invalid",    "wrong",       false },
            { "",           "password",    false },
            { "testuser",   "",            false },
        };
    }

    @Test(dataProvider = "loginData")
    public void testLogin(String username, String password,
                          boolean shouldPass) {
        driver.findElement(By.id("username")).sendKeys(username);
        driver.findElement(By.id("password")).sendKeys(password);
        driver.findElement(By.cssSelector("button[type='submit']")).click();

        if (shouldPass) {
            Assert.assertTrue(
                driver.getCurrentUrl().contains("/dashboard"),
                "Login should succeed for: " + username
            );
        } else {
            WebElement error = wait.until(
                ExpectedConditions.visibilityOfElementLocated(
                    By.cssSelector(".error-message")
                )
            );
            Assert.assertTrue(error.isDisplayed(),
                "Error should show for: " + username);
        }
    }
}

// Separate class for all test data
public class TestData {

    @DataProvider(name = "bankingUsers")
    public static Object[][] bankingUsers() {
        return new Object[][] {
            { "admin",    "admin123",   "Admin User" },
            { "john",     "john456",    "John Doe" },
            { "jane",     "jane789",    "Jane Smith" },
        };
    }

    @DataProvider(name = "searchTerms")
    public static Object[][] searchTerms() {
        return new Object[][] {
            { "Laptop",     3 },   // term, expectedMinResults
            { "Phone",      5 },
            { "xyz123abc",  0 },   // no results expected
        };
    }
}

// Test class uses DataProvider from another class
public class BankingLoginTest extends BaseTest {

    @Test(dataProvider = "bankingUsers",
          dataProviderClass = TestData.class)
    public void testUserLogin(String username, String password,
                              String expectedName) {
        driver.findElement(By.id("username")).sendKeys(username);
        driver.findElement(By.id("password")).sendKeys(password);
        driver.findElement(By.cssSelector("button[type='submit']")).click();

        WebElement welcome = wait.until(
            ExpectedConditions.visibilityOfElementLocated(
                By.id("welcome-message")
            )
        );
        Assert.assertTrue(
            welcome.getText().contains(expectedName),
            "Welcome message should contain: " + expectedName
        );
    }
}

import java.lang.reflect.Method;

@DataProvider(name = "portalData")
public static Object[][] getPortalData(Method method) {
    if (method.getName().equals("testBankingLogin")) {
        return new Object[][] {
            { "bankuser1", "bankpass1" },
            { "bankuser2", "bankpass2" },
        };
    } else if (method.getName().equals("testShoppingLogin")) {
        return new Object[][] {
            { "shopuser1", "shoppass1" },
            { "shopuser2", "shoppass2" },
        };
    }
    return new Object[][] {};
}

@Test(dataProvider = "portalData")
public void testBankingLogin(String user, String pass) {
    driver.get("https://www.testerrank.com/banking");
    // ... login with user/pass ...
}

@Test(dataProvider = "portalData")
public void testShoppingLogin(String user, String pass) {
    driver.get("https://www.testerrank.com/shopping");
    // ... login with user/pass ...
}

public class ShoppingCartTest extends BaseTest {

    @DataProvider(name = "cartScenarios")
    public Object[][] cartData() {
        return new Object[][] {
            // product,     qty,  expectedTotal
            { "Laptop",      1,   "$999.99" },
            { "Laptop",      2,   "$1,999.98" },
            { "T-Shirt",     3,   "$89.97" },
            { "Coffee Mug",  5,   "$64.95" },
        };
    }

    @Test(dataProvider = "cartScenarios",
          description = "Verify cart total calculation")
    public void testCartTotal(String product, int qty,
                              String expectedTotal) {
        driver.get("https://www.testerrank.com/shopping");

        // Search and add product
        driver.findElement(By.id("search")).sendKeys(product);
        driver.findElement(By.id("search-btn")).click();

        wait.until(ExpectedConditions.visibilityOfElementLocated(
            By.cssSelector(".product-card")
        ));

        WebElement quantityInput = driver.findElement(By.id("quantity"));
        quantityInput.clear();
        quantityInput.sendKeys(String.valueOf(qty));
        driver.findElement(By.id("add-to-cart")).click();

        // Verify total
        WebElement total = wait.until(
            ExpectedConditions.visibilityOfElementLocated(
                By.id("cart-total")
            )
        );
        Assert.assertEquals(total.getText(), expectedTotal,
            qty + "x " + product + " should total " + expectedTotal);
    }
}