Why do my Selenium tests fail intermittently?

Most flaky failures come from acting before the page is ready. Replace sleeps with explicit waits for the condition you need, and prefer stable locators such as ids and data attributes.

Selenium WebDriver Cheat Sheet: Locators, Waits, and Actions (Python and Java)

Introduction

Selenium WebDriver automates real browsers. This cheat sheet shows the same operations in Python and Java for Selenium 4, where Selenium Manager downloads matching browser drivers for you. Check the official Selenium documentation for your version.

Prerequisites

Python or Java basics
Chrome or another supported browser installed

Step-by-Step Guide

Step 1: Install and start a browser

With Selenium 4.6 and newer, Selenium Manager finds or downloads the right driver automatically.

# Python
pip install selenium

from selenium import webdriver
driver = webdriver.Chrome()
driver.get("https://example.com")
print(driver.title, driver.current_url)
driver.quit()

// Java (add the selenium-java dependency)
WebDriver driver = new ChromeDriver();
driver.get("https://example.com");
System.out.println(driver.getTitle());
driver.quit();

Step 2: Locators

Prefer id, name, and CSS selectors. XPath is powerful but more fragile.

# Python
from selenium.webdriver.common.by import By
driver.find_element(By.ID, "username")
driver.find_element(By.NAME, "email")
driver.find_element(By.CSS_SELECTOR, "form .btn-primary")
driver.find_element(By.XPATH, "//button[text()='Save']")
driver.find_element(By.LINK_TEXT, "Sign in")
driver.find_elements(By.CLASS_NAME, "item")      # list of elements

// Java
driver.findElement(By.id("username"));
driver.findElement(By.cssSelector("form .btn-primary"));
driver.findElement(By.xpath("//button[text()='Save']"));
driver.findElements(By.className("item"));

Step 3: Element actions

These work on any WebElement you have found.

# Python
el = driver.find_element(By.ID, "q")
el.clear()
el.send_keys("selenium")
el.click()
el.text
el.get_attribute("value")
el.is_displayed(); el.is_enabled(); el.is_selected()

from selenium.webdriver.common.keys import Keys
el.send_keys(Keys.ENTER)

// Java
el.clear(); el.sendKeys("selenium"); el.click();
el.getText(); el.getAttribute("value");
el.isDisplayed(); el.isEnabled();

Step 4: Waits

Use explicit waits for the exact condition you need. Avoid mixing them with implicit waits, and avoid sleep.

# Python
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

wait = WebDriverWait(driver, 10)
button = wait.until(EC.element_to_be_clickable((By.ID, "save")))
wait.until(EC.visibility_of_element_located((By.CSS_SELECTOR, ".toast")))
wait.until(EC.url_contains("dashboard"))

// Java
WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
WebElement button = wait.until(ExpectedConditions.elementToBeClickable(By.id("save")));
wait.until(ExpectedConditions.urlContains("dashboard"));

Step 5: Dropdowns, frames, windows, and alerts

Switch context before interacting with a frame, a new window, or an alert.

# Python
from selenium.webdriver.support.ui import Select
Select(driver.find_element(By.ID, "country")).select_by_visible_text("India")

driver.switch_to.frame("payment-frame")
driver.switch_to.default_content()

handles = driver.window_handles
driver.switch_to.window(handles[-1])

alert = driver.switch_to.alert
alert.accept()          # or alert.dismiss(), alert.text

// Java
new Select(driver.findElement(By.id("country"))).selectByVisibleText("India");
driver.switchTo().frame("payment-frame");
driver.switchTo().defaultContent();
driver.switchTo().alert().accept();

Step 6: Mouse and keyboard actions, options, and screenshots

ActionChains builds complex interactions. Browser options control headless mode and window size.

# Python
from selenium.webdriver import ActionChains
ActionChains(driver).move_to_element(menu).click(item).perform()
ActionChains(driver).double_click(el).perform()

options = webdriver.ChromeOptions()
options.add_argument("--headless=new")
options.add_argument("--window-size=1920,1080")
driver = webdriver.Chrome(options=options)

driver.save_screenshot("page.png")
driver.execute_script("window.scrollTo(0, document.body.scrollHeight)")

FAQs

Why do my Selenium tests fail intermittently?: Most flaky failures come from acting before the page is ready. Replace sleeps with explicit waits for the condition you need, and prefer stable locators such as ids and data attributes.

Summary

Start a driver with Selenium Manager, choose stable locators, use explicit waits instead of sleeps, switch context for frames, windows and alerts, and use ActionChains and options when needed.