Quick Learning guide: Python (Pytest) with Selenium Automation

1. Introduction to pytest and Selenium

What is pytest?

• pytest is a popular Python testing framework, known for its simplicity and scalability.
• It supports fixtures, parameterized testing, and has built-in plugins for advanced testing needs.

What is Selenium?

• Selenium is a widely used tool for automating web browsers.
• Supports various browsers (e.g., Chrome, Firefox) and programming languages.

Why pytest + Selenium?

• Easy test execution with detailed reporting.
• Reusable test setups with fixtures.
• Parameterized testing for testing multiple data sets.

2. Environment Setup

Install Required Libraries

pip install selenium pytest pytest-html

pip install webdriver-manager        

Install WebDriver

Use webdriver-manager to simplify driver management.

Example for ChromeDriver:

from selenium import webdriver

from selenium.webdriver.chrome.service import Service

from webdriver_manager.chrome import ChromeDriverManager

driver = webdriver.Chrome(service=Service(ChromeDriverManager().install()))

driver.get("https://example.com")

driver.quit()

3. Pytest Basics

Writing a Basic Test

File: test_example.py

def test_example():

    assert 1 + 1 == 2

Run the test:

pytest test_example.py

Key pytest Features:

Assertions: Use Python’s assert statement.

• Markers: Add metadata (e.g., @pytest.mark.smoke).
• Fixtures: Reusable setup and teardown logic.

4. Selenium with pytest

Example Test Case: Open a Website

File: test_google.py

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from webdriver_manager.chrome import ChromeDriverManager
 
def test_open_google():

    driver = webdriver.Chrome(service=Service(ChromeDriverManager().install()))
    driver.get("https://www.google.com")
    assert "Google" in driver.title
    driver.quit()        

5. Pytest Fixtures

What are Fixtures?

Fixtures help manage setup and teardown logic for tests.

Example: Browser Fixture

File: conftest.py

import pytest
from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from webdriver_manager.chrome import ChromeDriverManager

@pytest.fixture

def browser():

     driver = webdriver.Chrome(service=Service(ChromeDriverManager().install()))
     yield driver
     driver.quit()         

Use the fixture in your test:

 def test_open_google(browser):
     browser.get("https://www.google.com")
     assert "Google" in browser.title        

6. Locators in Selenium

• ID: driver.find_element(By.ID, "element_id")
• Name: driver.find_element(By.NAME, "element_name")
• XPath: driver.find_element(By.XPATH, "//tag[@attribute='value']")
• CSS Selector: driver.find_element(By.CSS_SELECTOR, "tag[attribute='value']")

Example

 from selenium.webdriver.common.by import By

def test_google_search(browser):

     browser.get("https://www.google.com")
     search_box = browser.find_element(By.NAME, "q")
     search_box.send_keys("pytest with Selenium")
     search_box.submit()
     assert "pytest" in browser.page_source        

7. Assertions in pytest

• Basic Assertions: assert 1 == 1

assert "Google" in driver.title        

• Custom Error Messages: assert "Bing" in driver.title, "Title did not contain Bing"

8. Parameterized Testing

Run tests with multiple sets of data.

Example

import pytest
@pytest.mark.parametrize("query", ["pytest", "Selenium", "Python"])
def test_search(browser, query):
    browser.get("https://www.google.com")
    search_box = browser.find_element(By.NAME, "q")
    search_box.send_keys(query)
    search_box.submit()
    assert query in browser.page_source        

9. Reports with pytest-html

Generate HTML reports for better insights.

Install pytest-html        

pip install pytest-html        

Run Tests with HTML Report

pytest --html=report.html        

10. Common Use Cases

Login Test

def test_login(browser):
    browser.get("https://example.com/login")
    browser.find_element(By.ID, "username").send_keys("test_user")
    browser.find_element(By.ID, "password").send_keys("password123")
    browser.find_element(By.ID, "login_button").click()
    assert "Welcome" in browser.page_source        

Form Submission

def test_form_submission(browser):
    browser.get("https://example.com/form")
    browser.find_element(By.NAME, "first_name").send_keys("John")
    browser.find_element(By.NAME, "last_name").send_keys("Doe")
    browser.find_element(By.NAME, "submit").click()
    assert "Thank you" in browser.page_source        

11. Handling Dynamic Waits

Implicit Waits

Sets a default wait time for all elements.

browser.implicitly_wait(10)  # Wait up to 10 seconds        

Explicit Waits

Waits for a specific condition to be met before proceeding.

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


def test_explicit_wait(browser):
     browser.get("https://example.com")
     element = WebDriverWait(browser, 10).until(
         EC.presence_of_element_located((By.ID, "dynamic_element"))
     )

    assert element is not None        

Fluent Waits

Checks for a condition at regular intervals until a timeout occurs.

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

def test_fluent_wait(browser):
    wait = WebDriverWait(browser, timeout=10, poll_frequency=1)
    element = wait.until(EC.presence_of_element_located((By.ID,      "dynamic_element")))
    assert element.is_displayed()        

12. Handling Alerts

Simple Alerts

alert = browser.switch_to.alert        

assert alert.text == "This is a simple alert"        

alert.accept()         

Confirmation Alerts

alert = browser.switch_to.alert        

alert.dismiss()  # Click 'Cancel'        

Prompt Alerts

alert = browser.switch_to.alert        

alert.send_keys("Test Input")        

alert.accept()        

13. Types of Exceptions and Handling

Common Selenium Exceptions

• NoSuchElementException: Element not found.
• TimeoutException: Wait timeout exceeded.
• StaleElementReferenceException: Element no longer attached to the DOM.
• ElementNotInteractableException: Element not interactable.

Handling Exceptions

Use try-except blocks to handle exceptions gracefully.

from selenium.common.exceptions import NoSuchElementException
def test_exception_handling(browser):
    try:
        browser.get("https://example.com")
        browser.find_element(By.ID, "non_existent_element")
    except NoSuchElementException:
        print("Element not found")        

14. Parallel Execution in pytest

Install pytest-xdist

 pip install pytest-xdist        

Run Tests in Parallel

pytest -n 4  # Runs tests in 4 parallel threads        

Example

If you have multiple test files, they will run concurrently:

pytest tests/ -n auto  # Automatically detect the number of available CPU cores        

15. Multi-Tab Handling

Automating scenarios involving multiple browser tabs.

Example

from selenium.webdriver.common.by import By

def test_multi_tab_handling(browser):
    browser.get("https://example.com")
    browser.execute_script("window.open('https://google.com', '_blank');")
    # Get all window handles
    tabs = browser.window_handles 
    # Switch to the new tab
    browser.switch_to.window(tabs[1])
    assert "Google" in browser.title
     # Switch back        

16. Best Practices

1. Use fixtures for setup and teardown.
2. Avoid hardcoding locators or test data.
3. Group tests with markers (e.g., @pytest.mark.smoke).
4. Use pytest-html for clear reporting.
5. Handle browser waits effectively (use WebDriverWait for dynamic elements).
6. Leverage parallel execution for faster test runs.