Selenium is one of the most powerful web automation tools any developer or tester would love to use for automating repetitive web tasks or validation of the behavior of web applications. The core functionality of Selenium is good enough for simple automation tasks, but advanced users can unlock more functionality using custom locators and assertions in Python. These advanced techniques allow the tester to interact with complex web elements more efficiently and ensure that their automation scripts are robust, maintainable, and scalable.

In this article, we will go through the advanced techniques of utilizing custom locators and assertions in Selenium Python automation and how you can navigate complex web applications, improve your test accuracy, and enhance coverage.

What Are Locators in Selenium?

Locators in Selenium refer to how you identify the buttons, input fields, checkboxes, etc. For interaction on the web page. Selenium WebDriver supports the following standard locator strategies.

Locators in Selenium are how you locate the buttons, input fields, checkboxes, and other things. For interaction on the web page. Locator is a strategy used in Selenium that defines how you will locate elements for interaction on the web page. Selenium WebDriver helps with the following standard locator strategies.

  • Link Text/Partial Link Text: Find links with the given link text.
  • CSS Selectors: Flexible locator, which is essentially a CSS rule.
  • XPath: This is a very powerful locator based on the actual XML path to an element.

But for complex or dynamic web application testing, the standard locators alone may not be enough. In such cases, also the test engineers should develop custom locators with unique and proper identification of elements as well.

Using Custom Locators in Selenium Python

Custom locators allow testers to create locators that are appropriate to the inherent structure and behavior of the target web application. Custom locators make your test scripts more accurate and more maintainable, especially for web applications that embed dynamic content or UI changes.

  • Using Dynamic XPath

Dynamic web applications are likely to generate dynamic values for an element at runtime. This makes it challenging to implement static locators. Dynamic XPath expressions help testers tackle such scenarios by locating elements based on a pattern rather than specific attributes.

For instance, if you have an ID that always changes whenever you open a session, and you want to find an element using that ID, you might not get away with setting a static ID. So, you can make use of the XPath expression by matching it partially or elements nearby like so:

# Locate element with dynamic ID by using contains() in XPath

element = driver.find_element_by_xpath(“//input[contains(@id, ‘dynamic_part’)]”)

This dynamic XPath finds an input field whose id holds a common string in the sessions, making this flexible enough to adapt to variations in the web page structure.

  • CSS Selectors Using Custom Attributes

Today’s web applications style or annotate elements with custom attributes data-*, aria-*. These can be quite effective locators via using CSS selectors for more detailed identification.

# Custom attribute ‘data-test’ used in CSS selector

element = driver.find_element_by_css_selector(“button[data-test=’submit-btn’]”)

This allows you to locate elements using attributes that are unique to a particular user interface component, even when other attributes, such as class names, are generated dynamically.

  • Locator combinations for more complex scenarios

Even some of the web elements cannot be located with a single locator. For such a scenario, you can use more than one locator in a single strategy. Selenium supports complex locator chains, such as finding an ancestor element to locate a particular child element.

For instance, consider that you need to locate a button within a specific portion of your webpage. For this purpose, you can combine the CSS locator along with the XPath locator as given below:

# Find button inside a div with class ‘header-section’

element = driver.find_element_by_xpath(“//div[@class=’header-section’]//button[@name=’submit’]”)

This method is especially useful in case you have similar elements on a web page or the structure is a bit complex, so here you could make sure to get the right element.

Assertions: Validate with Precision in Selenium Tests

Assertions are basically an integral part of checking whether the test has been passed or failed. This will help you determine whether the actual result matches the expected result, indicating if your automation script is correct or not.

  • Basic Assertions

In Selenium Python, assertions can be made using an assert statement in Python. A simple assertion statement could be as follows:

# Assert the text expected appears in the page title

assert “Home Page” in driver.title

This implies that the page title contains the expected text. The test will fail with an error if the assertion is not successful.

  • Custom Assertions to Assert Element Attributes

Assertions do not have to be used when checking that the titles of pages or URLs are correct. You can also assert some properties of specific web elements, like text: whether they are visible or enabled.

To check that a button is enabled and clickable:

# Check if the ‘Submit’ button is enabled

submit_button = driver.find_element_by_name(‘submit’)

assert submit_button.is_enabled(), “Submit button should be enabled

This is useful for preconditions in validating conditions before an action is performed, such as whether a button is interactive or whether a form field is editable.

  • More Advanced Assertions With WebDriverWait

Complex applications have elements that load asynchronously or depend on certain conditions to be met before they can be interacted with. At this point, normal assertions are perhaps too brittle to work because they run immediately before the element has a chance to finish rendering.

We could wait for a condition to be met using Selenium’s WebDriverWait and build even more complicated assertions.

Example usage: waiting until a button is clickable:

from selenium.webdriver.common.by import By

from selenium.webdriver.support.ui import WebDriverWait

from selenium.webdriver.support import expected_conditions as EC

wait until the button is clickable before asserting the presence of the button

from selenium import webdriver

driver = webdriver.Chrome()

WebDriverWait, combined with assertions, guarantees that your tests do not hang because of time issues and the page is in the right state when you interact with elements.

Best Practices for Test Robustness and Maintainability

As you use your custom locators and assertions with Selenium Python, there are a few things you can do to ensure your test scripts are maintainable and robust. Here are a few best practices to remember:

  • Page Object Model (POM)

This is a design pattern that initiates support for maintainability and scalability in your test scripts. POM represents each page of your web application as a class and locators and actions on that page get defined within the class itself.

With locators and actions being extracted into reusable classes, you avoid duplication, and changes to the structure of the web application need to be updated only in one place.

  • Parameterization for Reusability

Parameterization allows you to write flexible test scripts running across more than one dataset. In Selenium Python, you can use parameterized tests to test the same function with different inputs.

For example, suppose you were testing a login form. You could write a single test case that accepts various combinations of username and password. Then, you can reuse this test case for many scenarios by passing different values for username and password.

  • AVOIDING HARD-CODED VALUES

Hard coding values make your test scripts brittle and hard to maintain. Do not hard-code locators or test data values; instead, store them in variables, constants, or configuration files.

For instance, if a given URL in your application frequently changes, store the URL in a configuration file that can be independently changed in your test scripts.

The more complex your Selenium automation is, the more likely you are to require them to run cross-browser and cross-OS compatible. You would, therefore, look towards getting the platform that can give you access to thousands of browser environments for your automation so that you do not keep maintaining the physical infrastructure. With LambdaTest, an AI-powered cloud testing platform, you can utilize the cloud-based Selenium Grid to run your parallel tests, which can further improve the speed and efficiency of your automation testing. It is an AI-powered test orchestration and execution platform that allows you to perform automation testing with Selenium at a scale of over 3000+ environments.

Conclusion

Custom locators and assertions in Selenium Python prove to you how you can strengthen the correctness, strength, and maintainability of your automation scripts. Through advanced techniques like these, you’re able to consider more complex web applications and simulate UI behavior under varied conditions; this ensures thorough test coverage.

Together, these practices with scalable cloud platforms like LambdaTest can further optimize your testing process so that your web application works flawlessly across different browsers and devices. Applying these advanced strategies can take your Selenium Python automation to the next level and provide you with the power to carry out complex testing challenges much more easily.

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