Mastering Data-Driven Testing in Selenium with Java explained with structure

 Mastering Data-Driven Testing in Selenium with Java

1. What is Data-Driven Testing?

Data-driven testing (DDT) is a test automation approach where test data is separated from test scripts. Instead of hardcoding values into the test scripts, the test data is stored in external sources such as:

• Excel files (.xlsx)
• CSV files
• Databases (SQL, MongoDB, etc.)
• JSON or XML files
• Property files

This approach allows reusability, scalability, and better maintenance.

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2. Setting Up Data-Driven Testing in Selenium with Java

To perform DDT in Selenium with Java, you need the following dependencies:

Required Libraries

1. Selenium WebDriver - For automating web applications.
2. Apache POI (for Excel) - If using Excel files.
3. Jackson / Gson (for JSON) - If using JSON.
4. TestNG or JUnit - For running parameterized tests.

Maven Dependencies

Add these to pom.xml if you're using Maven:

xml

<dependencies>
    <!-- Selenium WebDriver -->
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-java</artifactId>
        <version>4.10.0</version>
    </dependency>

    <!-- Apache POI (for Excel files) -->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>5.2.3</version>
    </dependency>

    <!-- Jackson (for JSON handling) -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.15.2</version>
    </dependency>

    <!-- TestNG (for test execution) -->
    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>7.7.1</version>
        <scope>test</scope>
    </dependency>
</dependencies>

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3. Implementing Data-Driven Testing in Selenium with Java

A. Data-Driven Testing using Excel (Apache POI)

Steps to follow:

1. Read test data from an Excel file (.xlsx).
2. Use a utility method to fetch data from Excel.
3. Pass data dynamically to test cases.

Utility Class for Reading Excel File

java

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class ExcelUtils {
    public static String getCellData(String filePath, String sheetName, int row, int col) throws IOException {
        FileInputStream fis = new FileInputStream(new File(filePath));
        Workbook workbook = new XSSFWorkbook(fis);
        Sheet sheet = workbook.getSheet(sheetName);
        Cell cell = sheet.getRow(row).getCell(col);
        String data = cell.toString();
        workbook.close();
        return data;
    }
}

Selenium Test with Data from Excel

java

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import java.io.IOException;

public class DataDrivenTest {
    WebDriver driver;

    @BeforeClass
    public void setUp() {
        System.setProperty("webdriver.chrome.driver", "path/to/chromedriver");
        driver = new ChromeDriver();
    }

    @DataProvider(name = "loginData")
    public Object[][] getData() throws IOException {
        String filePath = "path/to/excel.xlsx";
        return new Object[][] {
            { ExcelUtils.getCellData(filePath, "Sheet1", 1, 0), ExcelUtils.getCellData(filePath, "Sheet1", 1, 1) },
            { ExcelUtils.getCellData(filePath, "Sheet1", 2, 0), ExcelUtils.getCellData(filePath, "Sheet1", 2, 1) }
        };
    }

    @Test(dataProvider = "loginData")
    public void loginTest(String username, String password) {
        driver.get("https://example.com/login");
        // Locate username, password fields and login button
        // driver.findElement(By.id("username")).sendKeys(username);
        // driver.findElement(By.id("password")).sendKeys(password);
        // driver.findElement(By.id("loginButton")).click();
    }

    @AfterClass
    public void tearDown() {
        driver.quit();
    }
}

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B. Data-Driven Testing using JSON (Jackson Library)

1. Store test data in a JSON file.
2. Read data using Jackson.
3. Pass it to the test.

Sample JSON File (data.json)

json

{
  "users": [
    { "username": "testuser1", "password": "pass123" },
    { "username": "testuser2", "password": "pass456" }
  ]
}

Utility Class for Reading JSON

java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.io.IOException;

public class JsonUtils {
    public static JsonNode readJsonFile(String filePath) throws IOException {
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.readTree(new File(filePath));
    }
}

Selenium Test Using JSON Data

java

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.AfterClass;
import org.testng.annotations.BeforeClass;
import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import com.fasterxml.jackson.databind.JsonNode;
import java.io.IOException;

public class DataDrivenJsonTest {
    WebDriver driver;

    @BeforeClass
    public void setUp() {
        System.setProperty("webdriver.chrome.driver", "path/to/chromedriver");
        driver = new ChromeDriver();
    }

    @DataProvider(name = "jsonData")
    public Object[][] getData() throws IOException {
        JsonNode users = JsonUtils.readJsonFile("path/to/data.json").get("users");
        Object[][] testData = new Object[users.size()][2];
        for (int i = 0; i < users.size(); i++) {
            testData[i][0] = users.get(i).get("username").asText();
            testData[i][1] = users.get(i).get("password").asText();
        }
        return testData;
    }

    @Test(dataProvider = "jsonData")
    public void loginTest(String username, String password) {
        driver.get("https://example.com/login");
        // Locate and interact with elements
    }

    @AfterClass
    public void tearDown() {
        driver.quit();
    }
}

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4. Best Practices for Data-Driven Testing

✅ Keep test data separate from scripts - Store data in external sources (Excel, JSON, etc.).
✅ Use Data Providers in TestNG - Makes tests reusable.
✅ Implement Utility Classes - Write reusable methods for reading different data sources.
✅ Use Logging - Use Log4j for debugging and logging test execution details.
✅ Handle Exceptions Properly - Always handle file exceptions (IOException, FileNotFoundException).
✅ Avoid Hardcoded File Paths - Use System.getProperty("user.dir") to get dynamic paths.

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5. Conclusion

• Excel + Apache POI: Best for structured tabular test data.
• JSON + Jackson: Best for API testing and dynamic datasets.
• TestNG DataProvider: Efficient way to run data-driven tests.
• Database-Driven: Best for real-time data testing (SQL/MongoDB).

Would you like help integrating a database-driven approach or handling CSV/XML files as well? 🚀