You mentioned that you fought with flaky tests. Can you tell more about that?

Flaky tests are tests that sometimes pass and sometimes fail without any changes in the code or test environment. I have encountered them in projects with UI automation and integration tests.

The main causes of flaky tests I have dealt with:

• Dependence on unstable external services or data.
• Timing issues: asynchronous operations, delays in loading elements.
• Improper cleanup of state between tests.
• Parallel execution of tests causing race conditions.

How I addressed them:

• Introduced explicit waits instead of fixed delays.
• Used mocking of external services to eliminate instability.
• Rewrote tests to be isolated and independent.
• Added logs and screenshots on failures for analysis.
• Implemented reruns of tests with a limit on the number of attempts.

Example of waiting for an element in Selenium with Python:

from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

wait = WebDriverWait(driver, 10)
element = wait.until(EC.visibility_of_element_located((By.ID, 'submit-button')))
element.click()

This approach significantly reduced false failures and increased the stability of the test suite.