Parameterized tests in Selenium Python

Introduction

Parameterized tests help you run the same test with different data easily. This saves time and avoids repeating code.

When you want to check a login form with multiple usernames and passwords.

When you need to test a search feature with different keywords.

When you want to verify a calculator app with many input values.

When you want to test form validation with various input combinations.

Syntax

Selenium Python

from pytest import mark

@mark.parametrize("input,expected", [
    (value1, expected1),
    (value2, expected2),
    # ... add more test cases
])
def test_function(input, expected):
    # test steps using input
    assert actual_result == expected

Use @mark.parametrize decorator from pytest to pass multiple data sets.

Each tuple in the list represents one test case with inputs and expected results.

Examples

This test checks if the square of a number matches the expected value.

Selenium Python

from pytest import mark

@mark.parametrize("number,expected", [
    (2, 4),
    (3, 9),
    (4, 16)
])
def test_square(number, expected):
    assert number * number == expected

This test tries to log in with different usernames and passwords using Selenium WebDriver.

Selenium Python

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

@mark.parametrize("username,password", [
    ("user1", "pass1"),
    ("user2", "pass2")
])
def test_login(username, password, driver):
    driver.get("https://example.com/login")
    driver.find_element(By.ID, "username").send_keys(username)
    driver.find_element(By.ID, "password").send_keys(password)
    driver.find_element(By.ID, "submit").click()
    assert "Welcome" in driver.page_source

Sample Program

This test opens a website and searches for different fruits. It checks if the search term appears in the page title after searching.

Selenium Python

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

@mark.parametrize("search_term", ["apple", "banana", "cherry"])
def test_search_function(search_term):
    driver = webdriver.Chrome()
    driver.get("https://www.example.com")
    search_box = driver.find_element(By.NAME, "q")
    search_box.clear()
    search_box.send_keys(search_term)
    search_box.submit()
    assert search_term in driver.title.lower()
    driver.quit()

Important Notes

Always close the browser after each test to avoid resource leaks.

Use clear and meaningful parameter names for readability.

Parameterized tests help find bugs with different inputs quickly.

Summary

Parameterized tests run the same test with many data sets.

They reduce repeated code and save time.

Use pytest's @mark.parametrize decorator for easy implementation.