Data-Driven Testing in Selenium

 📊 Data-Driven Testing in Selenium (Java)

✅ What is Data-Driven Testing?

Data-Driven Testing (DDT) is a software testing method where test data is stored in external files (like Excel, CSV, or databases), and the same test is run multiple times with different input values.

Purpose: To separate test logic from test data and increase test coverage with minimal code.

🔁 Benefits of Data-Driven Testing

Reduces code duplication

Easy to maintain and update data

Increases test coverage

Makes test cases reusable and flexible

📚 Common Data Sources in Selenium

Excel files (.xls or .xlsx)

CSV files

Databases (MySQL, SQL Server, etc.)

JSON / XML

Properties files

🧰 Tools You Need

Selenium WebDriver

TestNG (for test execution and @DataProvider)

Apache POI (for reading Excel files)

🧪 Example: Data-Driven Test with TestNG & DataProvider

java

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import org.testng.annotations.DataProvider;

import org.testng.annotations.Test;

public class LoginTest {

    @Test(dataProvider = "loginData")

    public void testLogin(String username, String password) {

        System.out.println("Testing login with: " + username + " / " + password);

        // WebDriver code to perform login

    }

    @DataProvider(name = "loginData")

    public Object[][] getLoginData() {

        return new Object[][] {

            {"user1", "pass1"},

            {"user2", "pass2"},

            {"user3", "pass3"}

        };

    }

}

📥 Reading Data from Excel using Apache POI

Step 1: Add Apache POI to your pom.xml (Maven):

xml

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<dependency>

    <groupId>org.apache.poi</groupId>

    <artifactId>poi-ooxml</artifactId>

    <version>5.2.3</version>

</dependency>

Step 2: Create Excel Reader Utility:

java

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import org.apache.poi.ss.usermodel.*;

import java.io.*;

public class ExcelUtils {

    public static Object[][] readExcel(String filePath, String sheetName) throws IOException {

        FileInputStream fis = new FileInputStream(filePath);

        Workbook workbook = WorkbookFactory.create(fis);

        Sheet sheet = workbook.getSheet(sheetName);

        int rowCount = sheet.getPhysicalNumberOfRows();

        int colCount = sheet.getRow(0).getLastCellNum();

        Object[][] data = new Object[rowCount - 1][colCount];

        for (int i = 1; i < rowCount; i++) {

            Row row = sheet.getRow(i);

            for (int j = 0; j < colCount; j++) {

                data[i - 1][j] = row.getCell(j).toString();

            }

        }

        workbook.close();

        fis.close();

        return data;

    }

}

Step 3: Use it in your Test Class:

java

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@DataProvider(name = "excelData")

public Object[][] getExcelData() throws IOException {

    return ExcelUtils.readExcel("testdata.xlsx", "Sheet1");

}

🧭 When to Use Data-Driven Testing?

Testing login forms with many credentials

Testing forms with various input combinations

Repeating the same test with different conditions

🧩 Alternative Tools for DDT

JUnit + CSV/Excel

Cucumber with Examples table

Selenium + TestNG + JSON/XML

✅ Summary

Feature Description

Test Framework TestNG, JUnit

Data Sources Excel, CSV, DB, JSON, XML

Main Benefit Reuse test code with multiple inputs

Popular Tool Apache POI (for Excel)

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