Assertions in Selenium Python: A Complete Guide

Assertions in Selenium Python tests: ensuring test reliability

Assertions play a key role in test automation, they ensure that the application under test behaves as expected during Selenium test execution. Assertions help identify differences between actual results and expected results, thereby increasing confidence in the reliability of the application.

What are assertions in Selenium Python?

Assertions in Selenium Python are statements used to verify the expected output of a test case against its actual result. These verifications are essential to verify that the application under test meets predefined criteria and are the cornerstone of automated testing.

Assertion types in Selenium Python

Selenium Python supports various types of assertions, each with its own unique use in test validation:

• Hard Assertions: When an assertion fails, execution stops immediately. This is ideal for critical verification where subsequent steps depend on the assertion results.
• Soft Assertions: Allow test execution to continue even if an assertion fails. This is useful for scenarios where multiple conditions need to be independently verified.

For example, you can use hard assertions to validate the page title and soft assertions to check multiple UI elements on the page.

Commonly used assertion methods in Python’s unittest framework

Python’s unittest framework provides a variety of assertion methods to effectively test various conditions:

• assertEqual(): Verify whether two values ​​are equal.
• assertTrue() and assertFalse(): Check whether the condition is true or false.
• assertIn(): Verify whether the item exists in the list or string.

Example:

• assertEqual(driver.title, "Home Page"): Confirm that the page title matches "Home Page".
• assertTrue(button.is_displayed()): Make sure the button is visible on the page.
• assertIn("Welcome", driver.page_source): Check whether the word "Welcome" exists in the page source code.

Writing Assertions in Selenium Python Tests

Writing assertions in Selenium Python tests involves combining Selenium commands with Python’s assertion methods. Two examples are given below:

1. Verify page title:

   <code class="language-python">
   from selenium import webdriver
   import unittest
   
   class Test</code>

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