Java Selenium TestNG CI/CD API Testing Database Playwright Performance

Chapter 4: Data-Driven Testing

Building a Complete Data-Driven Test

Time to put it all together. We will build a complete end-to-end data-driven test for the Banking Portal that uses ExcelUtils for test data, ConfigReader for configuration, a centralized DataProvider, and proper POM structure. This is what a real framework looks like.

The Project Structure

project-structuretext

src/
├── test/
│   ├── java/com/practice/
│   │   ├── base/
│   │   │   └── BaseTest.java          ← Browser setup + config
│   │   ├── pages/
│   │   │   ├── banking/
│   │   │   │   ├── LoginPage.java     ← Login page object
│   │   │   │   ├── DashboardPage.java ← Dashboard page object
│   │   │   │   └── TransferPage.java  ← Transfer page object
│   │   │   └── shopping/
│   │   │       ├── ShopHomePage.java   ← Shopping home page
│   │   │       └── CatalogPage.java   ← Search results page
│   │   ├── data/
│   │   │   └── DataProviders.java     ← All DataProviders
│   │   ├── utils/
│   │   │   ├── ExcelUtils.java        ← Excel reader
│   │   │   ├── CsvUtils.java          ← CSV reader
│   │   │   └── ConfigReader.java      ← Config reader
│   │   └── tests/
│   │       ├── banking/
│   │       │   ├── LoginTests.java     ← Login data-driven tests
│   │       │   └── TransferTests.java ← Transfer data-driven tests
│   │       └── shopping/
│   │           └── SearchTests.java   ← Search data-driven tests
│   └── resources/
│       ├── config.properties           ← Configuration
│       └── test-data/
│           ├── login-data.xlsx         ← Login test data
│           ├── transfer-data.xlsx      ← Transfer test data
│           └── search-terms.csv        ← Search test data

Step 1: Configuration

config.propertiestext

# src/test/resources/config.properties
base.url=https://www.testerrank.com
browser=chrome
headless=false
implicit.wait=5
explicit.wait=10
screenshot.on.failure=true
default.username=testuser
default.password=password123

Step 2: BaseTest with ConfigReader

src/test/java/com/practice/base/BaseTest.javajava

package com.practice.base;

import com.practice.utils.ConfigReader;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeOptions;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterMethod;
import org.testng.annotations.BeforeMethod;

import java.time.Duration;

public class BaseTest {
    protected WebDriver driver;

    @BeforeMethod
    public void setUp() {
        String browser = ConfigReader.get(
            "browser", "chrome");
        boolean headless = ConfigReader.getBoolean(
            "headless", false);

        driver = createDriver(browser, headless);
        driver.manage().window().maximize();
        driver.manage().timeouts().implicitlyWait(
            Duration.ofSeconds(
                ConfigReader.getInt("implicit.wait", 5)
            ));
    }

    private WebDriver createDriver(String browser,
                                    boolean headless) {
        return switch (browser.toLowerCase()) {
            case "firefox" -> new FirefoxDriver();
            default -> {
                ChromeOptions options = new ChromeOptions();
                if (headless) {
                    options.addArguments("--headless=new");
                }
                yield new ChromeDriver(options);
            }
        };
    }

    protected void navigateTo(String path) {
        String baseUrl = ConfigReader.get(
            "base.url", "https://www.testerrank.com");
        driver.get(baseUrl + path);
    }

    @AfterMethod
    public void tearDown() {
        if (driver != null) driver.quit();
    }
}

Step 3: Page Objects

src/test/java/com/practice/pages/banking/LoginPage.javajava

package com.practice.pages.banking;

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.ExpectedConditions;
import org.openqa.selenium.support.ui.WebDriverWait;

import java.time.Duration;

public class LoginPage {
    private final WebDriver driver;
    private final WebDriverWait wait;

    // Locators
    private final By usernameField = By.id("username");
    private final By passwordField = By.id("password");
    private final By loginButton =
        By.cssSelector("button[type='submit']");
    private final By errorMessage =
        By.cssSelector("[data-testid='error-message']");

    public LoginPage(WebDriver driver) {
        this.driver = driver;
        this.wait = new WebDriverWait(
            driver, Duration.ofSeconds(10));
    }

    public void enterUsername(String username) {
        WebElement field = wait.until(
            ExpectedConditions.visibilityOfElementLocated(
                usernameField));
        field.clear();
        field.sendKeys(username);
    }

    public void enterPassword(String password) {
        driver.findElement(passwordField).clear();
        driver.findElement(passwordField)
            .sendKeys(password);
    }

    public void clickLogin() {
        driver.findElement(loginButton).click();
    }

    public DashboardPage loginAs(String username,
                                  String password) {
        enterUsername(username);
        enterPassword(password);
        clickLogin();
        return new DashboardPage(driver);
    }

    public boolean isErrorDisplayed() {
        try {
            return wait.until(
                ExpectedConditions
                    .visibilityOfElementLocated(
                        errorMessage))
                .isDisplayed();
        } catch (Exception e) {
            return false;
        }
    }

    public String getErrorMessage() {
        return wait.until(
            ExpectedConditions
                .visibilityOfElementLocated(errorMessage))
            .getText();
    }
}

Step 4: Centralized DataProviders

src/test/java/com/practice/data/DataProviders.javajava

package com.practice.data;

import com.practice.utils.ExcelUtils;
import org.testng.annotations.DataProvider;

import java.io.IOException;

public class DataProviders {

    private static final String DATA_DIR =
        "src/test/resources/test-data/";

    @DataProvider(name = "bankingLoginData")
    public Object[][] bankingLoginData() throws IOException {
        return ExcelUtils.readSheet(
            DATA_DIR + "login-data.xlsx",
            "BankingLogin");
    }

    @DataProvider(name = "bankingTransferData")
    public Object[][] bankingTransferData()
            throws IOException {
        return ExcelUtils.readSheet(
            DATA_DIR + "transfer-data.xlsx",
            "Transfers");
    }
}

Step 5: The Data-Driven Test

src/test/java/com/practice/tests/banking/LoginTests.javajava

package com.practice.tests.banking;

import com.practice.base.BaseTest;
import com.practice.data.DataProviders;
import com.practice.pages.banking.DashboardPage;
import com.practice.pages.banking.LoginPage;
import org.testng.Assert;
import org.testng.annotations.Test;

public class LoginTests extends BaseTest {

    @Test(dataProvider = "bankingLoginData",
          dataProviderClass = DataProviders.class,
          description = "Verify login with multiple "
              + "credential combinations")
    public void testBankingLogin(
            String username, String password,
            String expectedResult,
            String expectedMessage) {

        navigateTo("/banking");
        LoginPage loginPage = new LoginPage(driver);

        loginPage.enterUsername(username);
        loginPage.enterPassword(password);
        loginPage.clickLogin();

        if ("success".equals(expectedResult)) {
            DashboardPage dashboard =
                new DashboardPage(driver);
            Assert.assertTrue(dashboard.isLoaded(),
                "Dashboard should load for user: "
                + username);
        } else {
            Assert.assertTrue(
                loginPage.isErrorDisplayed(),
                "Error should appear for user: "
                + username);
            if (expectedMessage != null
                    && !expectedMessage.isEmpty()) {
                Assert.assertEquals(
                    loginPage.getErrorMessage(),
                    expectedMessage,
                    "Error message mismatch for: "
                    + username);
            }
        }
    }
}

Step 6: testng.xml to Run It All

testng.xmlxml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suite SYSTEM "https://testng.org/testng-1.0.dtd">
<suite name="Banking Regression Suite">
    <test name="Banking Login Tests">
        <classes>
            <class name=
                "com.practice.tests.banking.LoginTests" />
        </classes>
    </test>
</suite>

<!-- Run: mvn test -DsuiteXmlFile=testng.xml -->
<!-- CI/CD: mvn test -DsuiteXmlFile=testng.xml
     -Dbase.url=https://staging.example.com
     -Dheadless=true -->

What Happens When You Run This

Maven starts TestNG with testng.xml
TestNG instantiates BaseTest, which reads config.properties via ConfigReader
ConfigReader checks System properties first (for CI/CD overrides)
BaseTest creates the browser based on config (chrome/firefox, headless/headed)
TestNG finds @Test with dataProviderClass = DataProviders.class
DataProviders.bankingLoginData() calls ExcelUtils.readSheet() to read the Excel file

This is the exact architecture interviewers expect you to describe. When they ask "Walk me through your framework," follow this flow: config.properties -> ConfigReader -> BaseTest -> Page Objects -> DataProviders -> ExcelUtils -> Test Class -> testng.xml. Cover each layer in 1-2 sentences.

Key Point: A complete data-driven framework has 6 layers: config, BaseTest, page objects, DataProviders, utils, and test classes.

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