Test functions and classes in Selenium Python

Introduction

Test functions and classes help organize your checks so you can find and fix problems easily.

When you want to check if a website button works correctly.

When you need to test multiple parts of a web page separately.

When you want to run the same test steps many times with different data.

When you want to keep your tests neat and easy to understand.

When you want to share setup steps like opening a browser for many tests.

Syntax

Selenium Python

import unittest

class TestExample(unittest.TestCase):
    def setUp(self):
        # Runs before each test
        pass

    def test_something(self):
        # Your test code here
        self.assertEqual(1, 1)

    def tearDown(self):
        # Runs after each test
        pass

if __name__ == '__main__':
    unittest.main()

Use setUp to prepare things before each test.

Use tearDown to clean up after each test.

Examples

A simple test function without a class using plain assert.

Selenium Python

def test_addition():
    assert 2 + 2 == 4

A test class with one test method using unittest assertions.

Selenium Python

import unittest

class TestMath(unittest.TestCase):
    def test_subtraction(self):
        self.assertEqual(5 - 3, 2)

A Selenium test class opening a browser, checking the title, then closing the browser.

Selenium Python

import unittest

class TestBrowser(unittest.TestCase):
    def setUp(self):
        from selenium import webdriver
        self.driver = webdriver.Chrome()

    def test_title(self):
        self.driver.get('https://example.com')
        self.assertIn('Example', self.driver.title)

    def tearDown(self):
        self.driver.quit()

Sample Program

This test opens the Chrome browser, goes to example.com, checks the page title contains 'Example Domain', then closes the browser.

Selenium Python

import unittest
from selenium import webdriver

class TestExampleDotCom(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()

    def test_title_contains_example(self):
        self.driver.get('https://example.com')
        self.assertIn('Example Domain', self.driver.title)

    def tearDown(self):
        self.driver.quit()

if __name__ == '__main__':
    unittest.main()

Important Notes

Always close the browser in tearDown to avoid leftover windows.

Use descriptive test method names starting with test_ so the test runner finds them.

Test classes help group related tests and share setup code.

Summary

Test functions and classes organize your checks clearly.

Use setUp and tearDown to prepare and clean up.

Run tests with unittest.main() to see results easily.

Practice

1. What is the main purpose of using test functions and classes in Selenium Python testing?

easy

A. To organize tests clearly and run them easily

B. To make the code run faster

C. To avoid writing any assertions

D. To skip browser setup

Solution

1. Step 1: Understand test organization

   Test functions and classes help group related tests logically.

2. Step 2: Recognize ease of running tests

   Using classes and functions allows running tests easily with frameworks like unittest.

3. Final Answer:

   To organize tests clearly and run them easily -> Option A

4. Quick Check:

   Test organization = To organize tests clearly and run them easily [OK]

Hint: Tests group checks for clarity and easy running [OK]

Common Mistakes:

• Thinking tests speed up code execution
• Believing assertions are optional
• Ignoring setup and teardown roles

2. Which of the following is the correct way to define a test method inside a unittest.TestCase class in Selenium Python?

easy

A. def test_example(self):

B. def example_test():

C. def TestExample(self):

D. def _test_example(self):

Solution

1. Step 1: Recall unittest naming conventions

   Test methods must start with 'test' and accept 'self' as first parameter.

2. Step 2: Check method definitions

   Only 'def test_example(self):' follows correct naming and signature.

3. Final Answer:

   def test_example(self): -> Option A

4. Quick Check:

   Method name starts with 'test' and has 'self' [OK]

Hint: Test methods start with 'test' and include self [OK]

Common Mistakes:

• Omitting 'self' parameter
• Not starting method name with 'test'
• Using uppercase 'Test' prefix

3. What will be the output when running this test code snippet?

import unittest

class MyTest(unittest.TestCase):
    def test_pass(self):
        self.assertEqual(2 + 2, 4)

    def test_fail(self):
        self.assertTrue(False)

if __name__ == '__main__':
    unittest.main(exit=False)

medium

A. Both tests pass

B. One test passes, one test fails

C. Both tests fail

D. Syntax error occurs

Solution

1. Step 1: Analyze test_pass method

   assertEqual(2 + 2, 4) is True, so test_pass passes.

2. Step 2: Analyze test_fail method

   assertTrue(False) fails, so test_fail fails.

3. Final Answer:

   One test passes, one test fails -> Option B

4. Quick Check:

   One True, one False assertion = One test passes, one test fails [OK]

Hint: Check each assertion's truth to predict pass/fail [OK]

Common Mistakes:

• Assuming all tests pass
• Ignoring assertTrue(False) fails
• Expecting syntax errors

4. Identify the error in this Selenium Python unittest code:

import unittest
from selenium import webdriver

class TestLogin(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()

    def test_login(self):
        self.driver.get('http://example.com')
        self.assertIn('Example', self.driver.title)

    def tearDown(self):
        self.driver.quit()

if __name__ == '__main__':
    unittest.main()

medium

A. webdriver.Chrome() requires path argument

B. Missing call to super() in setUp and tearDown

C. No error; code is correct

D. assertIn should be assertEquals

Solution

1. Step 1: Review setup and teardown methods

   setUp creates driver; tearDown quits it properly.

2. Step 2: Check assertion and webdriver usage

   assertIn checks substring in title correctly; webdriver.Chrome() works if driver is in PATH.

3. Final Answer:

   No error; code is correct -> Option C

4. Quick Check:

   Standard unittest setup and teardown used [OK]

Hint: Check if setup/teardown and assertions follow unittest rules [OK]

Common Mistakes:

• Assuming webdriver.Chrome() always needs path
• Confusing assertIn with assertEquals
• Forgetting to quit driver in tearDown

5. You want to run multiple Selenium tests that share the same browser setup and cleanup. Which unittest structure best achieves this?

hard

A. Call unittest.main() inside each test method

B. Write separate test functions without any setup or teardown

C. Create a new webdriver instance inside each test method

D. Use a TestCase class with setUpClass and tearDownClass class methods

Solution

1. Step 1: Understand shared setup/cleanup needs

   setUpClass and tearDownClass run once for all tests in a class, ideal for shared browser setup.

2. Step 2: Evaluate other options

   Separate functions lack shared setup; new webdriver per test is inefficient; unittest.main() runs all tests, not per method.

3. Final Answer:

   Use a TestCase class with setUpClass and tearDownClass class methods -> Option D

4. Quick Check:

   Shared setup/cleanup = setUpClass/tearDownClass [OK]

Hint: Use setUpClass/tearDownClass for shared browser setup [OK]

Common Mistakes:

• Creating driver in each test wastes resources
• Calling unittest.main() multiple times causes errors
• Skipping setup causes flaky tests