How To Handle Exceptions in Selenium Java, Ruby, Python, C#

It doesn’t take long when using Selenium before you run into errors from Selenium that may seem inexplicable (e.g., NoSuchElementException or StaleElementReferenceException). They can be a bit of a shock if you’re not sure what they are, how to handle them, or where to find documentation on how to address them.

By adding some simple exception handling we can catch Selenium’s errors and make our tests more resilient.

Let’s take a look at an example.

Example

For this example we’ll use a login example from the-internet.

Java

//ExceptionTest.java
import io.github.bonigarcia.wdm.WebDriverManager;
import org.openqa.selenium.By;
import org.openqa.selenium.NoSuchElementException;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.testng.Assert;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;

import java.util.concurrent.TimeUnit;

public class ExceptionTest {
  WebDriver driver;

  @BeforeTest
  public void beforeTest() {
  WebDriverManager.chromedriver().setup();

  driver = new ChromeDriver();
  driver.manage().window().maximize();
  driver.get(http://the-internet.herokuapp.com/login);

  }
  //Without exception handing
  @Test
  public void test1() {
  driver.findElement(By.id("username")).sendKeys("tomsmith");
  driver.findElement(By.id("password")).sendKeys("SuperSecretPassword!");
  driver.findElement(By.id("login")).submit();
  Assert.assertEquals( driver.findElement(By.id("login")).isDisplayed(),true);
  }
  //With exception handing
  @Test
  public void test2() {
  driver.get(http://the-internet.herokuapp.com/login);
  driver.findElement(By.id("username")).sendKeys("tomsmith");
  driver.findElement(By.id("password")).sendKeys("SuperSecretPassword!");
  driver.findElement(By.id("login")).submit();
  try {
  Assert.assertEquals( driver.findElement(By.id("login")).isDisplayed(),true);
  }
  catch (NoSuchElementException e)
  {
  e.printStackTrace();
  }
  }
  @AfterTest
  public void afterTest() {
  driver.quit();
  }

}

Python

# filename: exception_handling.py
import unittest
from selenium import webdriver
from selenium.common.exceptions import NoSuchElementException

class exception_handling(unittest.TestCase):
 
    def setUp(self):
        self.driver = webdriver.Firefox()
 
    def tearDown(self):
        self.driver.quit()
 
    def test_example_1(self):
        driver = self.driver
        driver.get('http://the-internet.herokuapp.com/lohin')
        driver.find_element_by_id('username').send_keys('tomsmith')
        driver.find_element_by_id('password').send_keys('SuperSecretPassword!')
        driver.find_element_by_id('login').click()
        self.assertEqual(driver.find_element_by_id('login').is_displayed(),True,'')
    def test_example_2(self):
        driver = self.driver
        driver.get('http://the-internet.herokuapp.com/lohin')
        driver.find_element_by_id('username').send_keys('tomsmith')
        driver.find_element_by_id('password').send_keys('SuperSecretPassword!')
        driver.find_element_by_id('login').click()
        try:
            self.assertEqual(driver.find_element_by_id('login').is_displayed(),True,'')
        except NoSuchElementException:
            print('Element Not found')

if __name__ == "__main__":
    unittest.main()

Ruby

# filename: exception_handling.rb

require 'selenium-webdriver'
require 'rspec/expectations'
include RSpec::Matchers

def setup
  @driver = Selenium::WebDriver.for :firefox
end

def teardown
  @driver.quit
end

def run
  setup
  yield
  teardown
end

#without exception handling
run do
  @driver.get 'http://the-internet.herokuapp.com/login'
  @driver.find_element(id: 'username').send_keys('tomsmith')
  @driver.find_element(id: 'password').send_keys('SuperSecretPassword!')
  @driver.find_element(id: 'login').submit
  expect(@driver.find_element(id: 'login').displayed?).to eql false
end
#with exception handling
run do
  @driver.get 'http://the-internet.herokuapp.com/login'
  @driver.find_element(id: 'username').send_keys('tomsmith')
  @driver.find_element(id: 'password').send_keys('SuperSecretPassword!')
  @driver.find_element(id: 'login').submit
  begin
    expect(@driver.find_element(id: 'login').displayed?).to eql false
  rescue Selenium::WebDriver::Error::NoSuchElementError
    false
  rescue Selenium::WebDriver::Error::StaleElementReferenceError
    false
  end
end

C#

// filename: ExceptionHanding.cs
using NUnit.Framework;
using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;
using System.Collections.Generic;
using System;
 
public class ExceptionHanding
{
    IWebDriver Driver;
 
    [SetUp]
    public void SetUp()
    {
        Driver = new FirefoxDriver();
    }
 
    [TearDown]
    public void TearDown()
    {
        Driver.Quit();
    }
    //without exception handling
    [Test]
    public void Example1()
    {
        Driver.Navigate().GoToUrl("http://the-internet.herokuapp.com/login");
        Driver.FindElement(By.Id("username")).SendKeys("tomsmith");
        Driver.FindElement(By.Id("password")).SendKeys("SuperSecretPassword!");
        Driver.FindElement(By.Id("login")).Submit();
        Assert.True(Driver.FindElement(By.Id("login")).Displayed);
     }
    //with exception handling
    [Test]
    public void Example2()
    {
        Driver.Navigate().GoToUrl("http://the-internet.herokuapp.com/login");
        Driver.FindElement(By.Id("username")).SendKeys("tomsmith");
        Driver.FindElement(By.Id("password")).SendKeys("SuperSecretPassword!");
        Driver.FindElement(By.Id("login")).Submit();
        try{
        Assert.True(Driver.FindElement(By.Id("login")).Displayed);
        }
        catch(NoSuchElementException e)
        {
          Console.WriteLine("Element not displayed")
        }
     }
}

If you save the file and run it here is what will happen:

Open the browser
Visit the page
Log in
Check to see that the login form is NOT displayed
Catch the exception from Selenium and return false instead
Complete the assertion using the boolean response (e.g., false)
Close the browser

Example

Java

Python

Ruby

C#

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