Parameterized tests in Selenium Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of parameterized Selenium test with multiple inputs

Consider this parameterized Selenium test using pytest. What will be the output when running this test suite?

Selenium Python

import pytest
from selenium.webdriver.common.by import By

@pytest.mark.parametrize('search_term', ['apple', 'banana'])
def test_search(browser, search_term):
    browser.get('https://example.com')
    search_box = browser.find_element(By.NAME, 'q')
    search_box.send_keys(search_term)
    search_box.submit()
    assert search_term in browser.title

A Both tests pass if page title contains 'apple' and 'banana' respectively

B Tests run but assertion always fails due to wrong locator

C Both tests fail because 'browser' fixture is not defined

D Only the first test runs because parameterization is incorrect

💡 Hint

Think about what is missing for the test to run properly with Selenium.

The test uses a 'browser' argument but does not define a fixture or setup for it. Without a browser fixture, pytest cannot provide the 'browser' object, so the tests will fail to run.

❓ assertion

intermediate

Correct assertion in parameterized test for form validation

You have a parameterized test that submits a form with different inputs. Which assertion correctly verifies that the error message appears when input is invalid?

Selenium Python

import pytest
from selenium.webdriver.common.by import By

@pytest.mark.parametrize('input_value, expect_error', [('', True), ('valid', False)])
def test_form_validation(browser, input_value, expect_error):
    browser.get('https://example.com/form')
    input_field = browser.find_element(By.ID, 'input')
    input_field.clear()
    input_field.send_keys(input_value)
    submit_button = browser.find_element(By.ID, 'submit')
    submit_button.click()
    error_elements = browser.find_elements(By.CLASS_NAME, 'error')
    # Which assertion is correct?

A assert (len(error_elements) > 0) == expect_error

B assert error_elements.text == expect_error

C assert error_elements.is_displayed() == expect_error

D assert error_elements.exists() == expect_error

💡 Hint

Remember that find_elements returns a list, not a single element.

find_elements returns a list of matching elements. To check if errors appear, verify if the list length is greater than zero and compare it to the expected error presence.

❓ locator

advanced

Best locator strategy for parameterized test with dynamic IDs

In a parameterized test, you need to locate a button whose ID changes dynamically but always starts with 'btn_'. Which locator is best to use?

A By.CLASS_NAME, 'btn_'

B By.ID, 'btn_' + dynamic_part

C By.XPATH, '//button[contains(@id, "btn_")]'

D By.CSS_SELECTOR, 'button[id^="btn_"]'

💡 Hint

Look for a locator that matches the start of the ID attribute.

CSS selector with ^= matches elements whose attribute starts with a given string. This is efficient and reliable for dynamic IDs starting with 'btn_'.

🔧 Debug

advanced

Debugging flaky parameterized Selenium test

A parameterized Selenium test intermittently fails with 'ElementNotInteractableException' on clicking a button. What is the most likely cause?

Selenium Python

import pytest
from selenium.webdriver.common.by import By

@pytest.mark.parametrize('page', ['home', 'about'])
def test_click_button(browser, page):
    browser.get(f'https://example.com/{page}')
    button = browser.find_element(By.ID, 'start')
    button.click()
    assert 'Started' in browser.page_source

A The parameterization syntax is invalid causing test failure

B The button is not visible or ready when click is attempted

C The locator ID 'start' is incorrect on some pages

D The assertion is wrong and causes false failures

💡 Hint

Consider timing and element readiness in Selenium tests.

ElementNotInteractableException usually means the element is present but not interactable yet, often due to page loading or animations. Adding waits can fix this.

❓ framework

expert

Implementing parameterized tests with pytest and Selenium for multiple browsers

You want to run the same parameterized test on Chrome and Firefox browsers using pytest and Selenium. Which pytest fixture setup correctly supports this?

A Use @pytest.mark.parametrize('browser_name', ['chrome', 'firefox']) and a fixture that initializes WebDriver based on browser_name

B Create separate test functions for each browser without parameterization

C Use a global variable to switch browsers inside the test

D Use Selenium Grid without any pytest parameterization

💡 Hint

Think about combining pytest parameterization with fixtures for browser setup.

Parametrizing the browser name and using a fixture to initialize the correct WebDriver allows running the same test on multiple browsers cleanly.