Conftest for shared fixtures in Selenium Python - Build an Automation Script

Automate login test using shared fixture from conftest.py

Preconditions (3)

Step 1: Open the browser using the shared fixture from conftest.py

Step 2: Navigate to 'https://example.com/login'

Step 3: Enter 'testuser' in the username input field with id 'username'

Step 4: Enter 'Test@1234' in the password input field with id 'password'

Step 5: Click the login button with id 'loginBtn'

Step 6: Wait until the URL changes to 'https://example.com/dashboard'

Step 7: Verify that the page title contains 'Dashboard'

✅ Expected Result: User is successfully logged in and redirected to the dashboard page with correct title

Automation Requirements - pytest with Selenium

Assertions Needed:

Assert current URL is 'https://example.com/dashboard'

Assert page title contains 'Dashboard'

Best Practices:

Use conftest.py to define a shared fixture for WebDriver setup and teardown

Use explicit waits to wait for URL change or page elements

Use pytest assertions for validation

Keep test code clean and readable

Automated Solution

Selenium Python

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

# conftest.py
@pytest.fixture(scope='session')
def driver():
    driver = webdriver.Chrome()
    driver.maximize_window()
    yield driver
    driver.quit()

# test_login.py

def test_login(driver):
    driver.get('https://example.com/login')
    username_input = WebDriverWait(driver, 10).until(
        EC.visibility_of_element_located((By.ID, 'username'))
    )
    username_input.send_keys('testuser')
    password_input = driver.find_element(By.ID, 'password')
    password_input.send_keys('Test@1234')
    login_button = driver.find_element(By.ID, 'loginBtn')
    login_button.click()

    WebDriverWait(driver, 10).until(
        EC.url_to_be('https://example.com/dashboard')
    )

    assert driver.current_url == 'https://example.com/dashboard', 'URL did not change to dashboard'
    assert 'Dashboard' in driver.title, 'Page title does not contain Dashboard'

The conftest.py file defines a driver fixture that sets up the Chrome WebDriver once per test session and quits it after all tests finish. This avoids repeating setup code in every test.

The test test_login uses this shared driver fixture. It opens the login page, waits explicitly for the username input to be visible, then enters the username and password. It clicks the login button and waits explicitly until the URL changes to the dashboard URL.

Finally, it asserts that the current URL is exactly the dashboard URL and that the page title contains the word 'Dashboard'. These assertions confirm the login was successful.

Explicit waits ensure the test does not fail due to timing issues. Using the shared fixture keeps the code clean and reusable.

Common Mistakes - 4 Pitfalls

Not using a shared fixture and creating WebDriver instance inside each test

Using implicit waits or time.sleep instead of explicit waits

Hardcoding URLs or credentials inside the test without flexibility

Using incorrect locator strategies or invalid selectors

Bonus Challenge

Now add data-driven testing with 3 different sets of login credentials (valid and invalid) using pytest parametrize

Show Hint

Practice

1. What is the main purpose of a conftest.py file in Selenium Python testing?

easy

A. To hold shared fixtures for setup and cleanup across multiple test files

B. To store test data in JSON format

C. To define Selenium WebDriver locators

D. To write test cases directly

Solution

1. Step 1: Understand the role of conftest.py

   The conftest.py file is used to define fixtures that can be shared across multiple test files for setup and cleanup tasks.

2. Step 2: Differentiate from other files

   It does not store test data, locators, or test cases directly but provides reusable setup code like browser initialization.

3. Final Answer:

   To hold shared fixtures for setup and cleanup across multiple test files -> Option A

4. Quick Check:

   conftest.py = shared fixtures [OK]

Hint: Remember: conftest.py shares setup code across tests [OK]

Common Mistakes:

• Confusing conftest.py with test case files
• Thinking conftest.py stores test data
• Using conftest.py to write test assertions

2. Which of the following is the correct way to declare a fixture in conftest.py using pytest?

easy

A. def browser(): yield webdriver.Chrome()

B. @pytest.fixture
def browser(): yield webdriver.Chrome()

C. fixture browser(): yield webdriver.Chrome()

D. @fixture def browser(): return webdriver.Chrome()

Solution

1. Step 1: Identify correct fixture decorator usage

   pytest fixtures require the @pytest.fixture decorator above the function to mark it as a fixture.

2. Step 2: Check syntax correctness

   @pytest.fixture def browser(): yield webdriver.Chrome() correctly uses @pytest.fixture and a generator with yield to provide the resource.

3. Final Answer:

   @pytest.fixture\ndef browser(): yield webdriver.Chrome() -> Option B

4. Quick Check:

   Use @pytest.fixture decorator [OK]

Hint: Always prefix fixture functions with @pytest.fixture [OK]

Common Mistakes:

• Omitting @pytest.fixture decorator
• Using wrong decorator name like @fixture
• Not using yield for setup/teardown

3. Given this fixture in conftest.py:

@pytest.fixture
def browser():
    driver = webdriver.Chrome()
    yield driver
    driver.quit()

What happens when a test uses this fixture?

medium

A. The browser never opens because yield is missing

B. The browser opens and closes immediately before the test runs

C. The browser opens but never closes

D. The browser opens before the test and closes after the test finishes

Solution

1. Step 1: Understand yield in fixture

   The yield statement pauses the fixture, providing the driver to the test, then resumes after the test to run cleanup.

2. Step 2: Analyze setup and teardown

   Driver is created before yield (browser opens), and driver.quit() runs after test finishes (browser closes).

3. Final Answer:

   The browser opens before the test and closes after the test finishes -> Option D

4. Quick Check:

   yield = setup before, cleanup after [OK]

Hint: yield splits setup and teardown in fixtures [OK]

Common Mistakes:

• Thinking yield closes browser immediately
• Forgetting driver.quit() after yield
• Assuming browser stays open forever

4. You wrote this fixture in conftest.py:

@pytest.fixture
def browser():
    driver = webdriver.Chrome()
    return driver
    driver.quit()

What is the problem with this fixture?

medium

A. driver.quit() is never called, so browser stays open after tests

B. Syntax error because return and yield cannot be used together

C. Fixture will not provide the driver to tests

D. driver.quit() runs before driver is created

Solution

1. Step 1: Analyze return and driver.quit() placement

   Since return exits the function immediately, driver.quit() after it never runs.

2. Step 2: Understand impact on browser lifecycle

   Without driver.quit(), the browser stays open after tests, causing resource leaks.

3. Final Answer:

   driver.quit() is never called, so browser stays open after tests -> Option A

4. Quick Check:

   return ends function before cleanup [OK]

Hint: Use yield, not return, to ensure cleanup runs [OK]

Common Mistakes:

• Placing driver.quit() after return
• Using return instead of yield for fixtures
• Expecting cleanup code after return to run

5. You want to share a browser fixture in conftest.py that opens Chrome once per test session and closes it after all tests finish. Which fixture scope and code is correct?

hard

A. @pytest.fixture(scope='function')
def browser():
driver = webdriver.Chrome()
yield driver
driver.quit()

B. @pytest.fixture(scope='module')
def browser():
driver = webdriver.Chrome()
driver.quit()
yield driver

C. @pytest.fixture(scope='session')
def browser():
driver = webdriver.Chrome()
yield driver
driver.quit()

D. @pytest.fixture(scope='session')
def browser():
driver = webdriver.Chrome()
driver.quit()
yield driver

Solution

1. Step 1: Choose correct fixture scope for session-wide browser

   Using scope='session' makes the fixture run once per test session.

2. Step 2: Verify setup and teardown order with yield

   Driver is created before yield (browser opens), and driver.quit() runs after all tests finish.

3. Final Answer:

   @pytest.fixture(scope='session')\ndef browser():\n driver = webdriver.Chrome()\n yield driver\n driver.quit() -> Option C

4. Quick Check:

   scope='session' + yield = one browser per session [OK]

Hint: Use scope='session' and yield for one browser per session [OK]

Common Mistakes:

• Using scope='function' for session-wide browser
• Calling driver.quit() before yield
• Yielding after driver.quit()