Why Use Logging in Selenium?

Logging is essential in Selenium automation for:
✔️ Debugging: Helps identify issues in test execution.
✔️ Tracking Execution: Records test steps and results.
✔️ Reporting: Provides test execution logs for analysis.
✔️ Better Maintenance: Helps in understanding failures over time.

Logging Methods in Selenium

✅ Using System.out.println() (Basic Logging)

Using System.out.println() is the simplest way to log messages.

Example:

System.out.println("Test started...");

❌ Limitations:

  • No log levels (INFO, ERROR, DEBUG).
  • Difficult to track logs in large projects.
  • No file storage for logs.

✅ Using Apache Log4j (Most Recommended)

Apache Log4j is a powerful logging framework that supports different log levels (INFO, DEBUG, ERROR, etc.).

Step 1: Add Log4j Dependency

For Maven projects, add this in pom.xml:

<dependencies>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.14.1</version>
    </dependency>
</dependencies>

Step 2: Create a Log4j Configuration File (log4j2.xml)

Save this in the resources folder.

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5level - %msg%n" />
        </Console>
        <File name="File" fileName="logs/test.log">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5level - %msg%n" />
        </File>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <AppenderRef ref="Console" />
            <AppenderRef ref="File" />
        </Root>
    </Loggers>
</Configuration>

✅ Logs are stored in logs/test.log.

Step 3: Implement Logging in Selenium Test

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.openqa.selenium.*;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.annotations.*;

public class Log4jTest {
    WebDriver driver;
    private static final Logger log = LogManager.getLogger(Log4jTest.class);

    @BeforeMethod
    public void setup() {
        System.setProperty("webdriver.chrome.driver", "path/to/chromedriver");
        driver = new ChromeDriver();
        log.info("Browser launched");
        driver.get("https://example.com");
        log.info("Navigated to website");
    }

    @Test
    public void testLogging() {
        try {
            WebElement element = driver.findElement(By.id("nonexistent"));
            element.click();
        } catch (NoSuchElementException e) {
            log.error("Element not found: " + e.getMessage());
        }
    }

    @AfterMethod
    public void teardown() {
        driver.quit();
        log.info("Browser closed");
    }
}

📌 Log Levels Used:
✔️ log.info() → General messages.
✔️ log.debug() → Debugging info.
✔️ log.warn() → Warnings.
✔️ log.error() → Errors in execution.

✅ Using Java’s Logger Class (Basic Alternative)

import java.util.logging.Logger;

public class JavaLoggerExample {
    private static final Logger logger = Logger.getLogger(JavaLoggerExample.class.getName());

    public static void main(String[] args) {
        logger.info("This is an info message");
        logger.warning("This is a warning");
    }
}

✅ Pros: Simple, no external libraries required.
❌ Cons: Lacks advanced features like file logging.

✅ Using Log4j with TestNG Reports

You can integrate Log4j logs into TestNG reports using ITestListener.

Step 1: Create a Listener Class

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.testng.ITestListener;
import org.testng.ITestResult;

public class TestNGListener implements ITestListener {
    private static final Logger log = LogManager.getLogger(TestNGListener.class);

    @Override
    public void onTestFailure(ITestResult result) {
        log.error("Test failed: " + result.getName());
    }

    @Override
    public void onTestSuccess(ITestResult result) {
        log.info("Test passed: " + result.getName());
    }
}

Step 2: Apply Listener to Test Class

import org.testng.annotations.*;

@Listeners(TestNGListener.class)
public class TestWithListener {
    @Test
    public void sampleTest() {
        System.out.println("Executing test...");
    }
}

✅ Logs automatically appear in TestNG reports.

Conclusion

Logging Method
Features
Use Case
System.out.println()
Basic console output
Small projects
Java Logger
Basic logging with levels
Simple applications
Log4j ✅
Advanced logging, supports files, integration with TestNG
Recommended for Selenium projects

🔹 Best Practice: Use Log4j with TestNG for scalable logging.