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What is WebDriver? Developer Guide

What is WebDriver

WebDriver is a tool that allows you to automate testing of websites and web applications. It lets you write scripts that can automatically interact with web pages – clicking buttons, entering text, navigating between pages, and checking if things appear correctly on the page. This makes it much faster and easier to thoroughly test websites compared to doing it all manually.WebDriver is most commonly used for automated testing of websites, but it can also be used for web scraping (automatically extracting data from websites) and automating other repetitive web-based tasks.

How WebDriver Works

Under the hood, WebDriver works by sending commands to a web browser to make it perform actions and retrieve information. It acts like a human user controlling the browser. The key components are:

  • The WebDriver script – This is code you write in a programming language like Python, Java, C#, Ruby, etc. It uses the WebDriver API to give instructions to the browser.
  • Browser driver – This is a separate program that acts as a bridge between your script and the actual web browser. Each browser has its own driver (e.g. ChromeDriver for Google Chrome, GeckoDriver for Firefox).
  • Web browser – This is the actual browser program like Chrome, Firefox, Safari, Edge, etc. that gets automated.

When you run your WebDriver script, it connects to the browser driver, which then launches or connects to the browser and passes along the commands from your script. The browser performs the instructed actions and sends information back, which gets passed back to your script via the driver.

Advantages of Using WebDriver

The main benefits of using WebDriver for testing include:

  • It allows you to automate repetitive manual tests, greatly speeding up test execution.
  • Tests can run unattended, even overnight or on remote machines.
  • You can test multiple browsers and operating system configurations.
  • Tests are written in standard programming languages, allowing complex logic.
  • It’s open-source and has a large community, with support for all major browsers.
  • It can be integrated with testing frameworks and CI/CD pipelines.

Compared to other types of automated testing, WebDriver has the advantage of actually driving the browser from the user’s perspective. This makes the tests very realistic and able to test even complex, highly dynamic modern web apps.

Setting Up WebDriver

To start using WebDriver, you need to:

  1. Choose a programming language and set up its environment. Popular choices are Python, Java, C#, JavaScript (Node.js), and Ruby.
  2. Install the WebDriver library for your language, e.g. Selenium WebDriver for Python, Java, C#, etc.
  3. Download the appropriate browser driver for the browser(s) you want to automate. Make sure to match the version to your browser version.
  4. Write your first script to launch the browser and navigate to a URL.

Here’s what that first script might look like in Python:


from selenium import webdriver

driver = webdriver.Chrome() # Launch Chrome
driver.get(“https://www.example.com”) # Navigate to a URL
driver.quit() # Quit the browser

This assumes you have ChromeDriver installed and on your system path. The script launches Chrome, navigates to https://www.example.com, and then quits the browser.

Finding Elements on the Page

One of the core things you’ll do with WebDriver is locate elements on web pages in order to interact with them. WebDriver provides several methods for finding elements based on their properties. The main locator methods are:

  • find_element(By.ID, "id") – finds an element by its id attribute
  • find_element(By.NAME, "name") – finds an element by its name attribute
  • find_element(By.CLASS_NAME, "class") – finds an element by one of its CSS class names
  • find_element(By.TAG_NAME, "tag") – finds an element by its HTML tag name
  • find_element(By.LINK_TEXT, "text") – finds a link element by its exact text content
  • find_element(By.PARTIAL_LINK_TEXT, "text") – finds a link element if its text content contains the given substring
  • find_element(By.CSS_SELECTOR, "selector") – finds an element by a CSS selector
  • find_element(By.XPATH, "xpath") – finds an element by an XPath expression

Each of these will return the first matching element on the page, or raise an exception if no matching element is found. There are also corresponding find_elements methods that return a list of all matching elements. For example, to find the search input on the Google homepage you could use:
search_box = driver.find_element(By.NAME, "q")

Best Practices for Locating Elements

When choosing how to locate elements, you should prefer attributes that are designed to be used for identification, like id, name, or a dedicated data-* attribute. Avoid using generic attributes like class or tag unless they are unique to the element you want. CSS selectors and XPath expressions are very powerful and can locate elements based on their position in the document structure. However, they can be brittle if the page structure changes. It’s often better to add dedicated test IDs to elements and use those. Always try to choose the most specific locator possible to ensure you get the right element even if the page changes slightly. And if you find yourself using the same complex selector multiple times, consider refactoring it into a helper function.

Interacting with Elements

Once you’ve found an element, you can interact with it in various ways:

  • element.click() – clicks on the element
  • element.send_keys("text") – types into a text input or textarea
  • element.clear() – clears the text from an input or textarea
  • element.submit() – submits a form
  • element.is_selected() – checks if a checkbox or radio button is selected
  • element.is_enabled() – checks if an element is enabled
  • element.is_displayed() – checks if an element is visible on the page
  • element.get_attribute("name") – gets the value of an element’s attribute
  • element.text – gets the text content of an element

For example, to search for “WebDriver” on Google:
search_box = driver.find_element(By.NAME, "q")
search_box.send_keys("WebDriver")
search_box.submit()

This finds the search input, types “WebDriver” into it, and then submits the form.

Waiting for Elements

One common issue when interacting with web pages is that elements may not be immediately available when the page loads. The page may be slow to load, or the element may be created dynamically by JavaScript some time after the initial load. To handle this, WebDriver provides explicit waits. An explicit wait makes WebDriver pause until a certain condition is met, or until a timeout is reached. The condition is typically the presence or visibility of a certain element. For example:
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

wait = WebDriverWait(driver, 10)
element = wait.until(EC.presence_of_element_located((By.ID, “myElement”)))

This will make WebDriver wait up to 10 seconds for an element with the ID “myElement” to be present on the page. If the element is found, it is returned. If the timeout is reached without finding the element, an exception is raised. There are many other expected conditions available, such as visibility_of_element_located, element_to_be_clickable, title_contains, etc.Using explicit waits is generally preferred over implicit waits (which make WebDriver wait a default amount of time after every action) or hard-coded time.sleep() calls. Explicit waits make your tests more reliable and efficient.

Testing with WebDriver

WebDriver is most commonly used for automated testing of web applications. You can write test scripts that navigate through your application, interact with elements, and check that the correct behavior occurs. A typical test script using WebDriver will:

  1. Launch a browser and navigate to the starting page of the application.
  2. Find elements on the page and interact with them (click buttons, enter text, etc.).
  3. Wait for the page to update or new elements to appear.
  4. Check that the expected changes occurred (new page loaded, message displayed, etc.).
  5. Repeat steps 2-4 to test a complete user journey or scenario.
  6. Quit the browser.

For example, a simple test for a login form might look like:

def test_login():
driver = webdriver.Chrome()
driver.get("https://www.example.com/login")
username_input = driver.find_element(By.ID, "username")
password_input = driver.find_element(By.ID, "password")
submit_button = driver.find_element(By.CSS_SELECTOR, "button[type='submit']")
username_input.send_keys("testuser")
password_input.send_keys("secret")
submit_button.click()
wait = WebDriverWait(driver, 10)
welcome_message = wait.until(EC.visibility_of_element_located((By.CLASS_NAME, "welcome")))
assert "Welcome, testuser!" in welcome_message.text
driver.quit()

This test checks that a user can log in with valid credentials and that they see a welcome message with their username afterwards.

Organizing Tests

As you write more tests, it’s important to keep them organized and maintainable. Some best practices include:

  • Use a test framework like Python’s unittest or pytest to structure your tests and handle setup/teardown.
  • Put reusable setup and teardown code in setUp and tearDown methods or @before and @after hooks.
  • Use Page Object Model pattern to encapsulate interactions with each page or component in a separate class.
  • Keep tests independent – each test should be able to run on its own and not depend on other tests.
  • Use descriptive names for test methods that explain the scenario being tested.
  • Keep tests focused – each test should check one specific thing. Use multiple assertions if needed.
  • Avoid hard-coded waits – use explicit waits instead.
  • Handle exceptions gracefully and provide meaningful error messages.

With well-structured and maintained tests, WebDriver can provide a powerful way to ensure the quality and reliability of your web application.

Conclusion

WebDriver is a versatile tool for automating interaction with web browsers, most commonly used for automated testing of web applications. Its ability to realistically simulate a user’s actions makes it invaluable for ensuring the quality and reliability of modern web apps. While there is a learning curve to using WebDriver effectively, the time invested is well worth it for the benefits of faster, more thorough, and more reliable testing. By following best practices around locating elements, handling waits, and structuring tests, you can create a robust suite of automated tests that will give you confidence in your application’s behavior. Beyond testing, WebDriver can also be used for tasks like web scraping or automating repetitive web-based processes. Its flexibility and wide language support make it a tool that every web developer or QA engineer should have in their toolkit. As web applications continue to grow in complexity and importance, tools like WebDriver will only become more essential for ensuring their quality and reliability. Mastering WebDriver is a valuable skill for anyone working in web development today.

About author

Rojer is a programmer by profession, but he likes to research new things and is also interested in writing. Devdeeds is his blog, where he writes all the blog posts related to technology, gadgets, mobile apps, games, and related content.

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