Parameterize with test data in Selenium Python - Framework Patterns

Framework Mode - Parameterize with test data

Folder Structure

selenium-python-project/
├── src/
│   ├── pages/
│   │   └── login_page.py
│   ├── tests/
│   │   └── test_login.py
│   ├── utils/
│   │   └── test_data.py
│   └── config/
│       └── config.yaml
├── reports/
├── drivers/
│   └── chromedriver.exe
├── requirements.txt
└── pytest.ini
    

Test Framework Layers

• Driver Layer: Manages browser drivers and WebDriver setup/teardown.
• Page Objects: Classes representing web pages with locators and actions.
• Tests: Test scripts using pytest with parameterized test data.
• Utilities: Helper modules, including test data providers for parameterization.
• Configuration: Environment settings, browser options, credentials stored in config files.

Configuration Patterns

Use config.yaml to store environment URLs, browser types, and credentials.

Example config.yaml:

environments:
  dev:
    url: "https://dev.example.com"
  prod:
    url: "https://www.example.com"
browser: chrome
credentials:
  username: "testuser"
  password: "password123"
    

Load config in tests and utilities to select environment and browser dynamically.

Test data for parameterization is stored in utils/test_data.py as lists or dictionaries.

Test Reporting and CI/CD Integration

• Use pytest with pytest-html plugin to generate HTML reports.
• Reports saved in reports/ folder with timestamps for easy tracking.
• Integrate tests in CI/CD pipelines (e.g., GitHub Actions, Jenkins) to run tests on code push.
• Parameterization allows running tests with multiple data sets automatically in CI.

Best Practices for Parameterizing with Test Data

• Keep test data separate from test logic for easy updates and readability.
• Use @pytest.mark.parametrize decorator to run tests with multiple inputs.
• Use descriptive test case names to identify which data set failed.
• Store sensitive data securely and avoid hardcoding credentials in test scripts.
• Validate test data format and completeness before running tests to avoid false failures.

Self Check

Where would you add a new set of login credentials to test multiple user types in this framework structure?

Key Result

Separate test data from test logic and use pytest parameterization to run tests with multiple data sets.

Practice

1. What is the main purpose of using @pytest.mark.parametrize in Selenium Python tests?

easy

A. To run tests in parallel threads

B. To skip tests that are not ready

C. To run the same test function multiple times with different input data

D. To generate HTML reports automatically

Solution

1. Step 1: Understand the decorator's role

   @pytest.mark.parametrize allows running one test function multiple times with different sets of input data.

2. Step 2: Compare with other options

   Skipping tests, running in parallel, or generating reports are different pytest features, not related to parameterization.

3. Final Answer:

   To run the same test function multiple times with different input data -> Option C

4. Quick Check:

   Parameterize = run test with many inputs [OK]

Hint: Parameterize means run test repeatedly with different data [OK]

Common Mistakes:

• Confusing parameterize with skipping tests
• Thinking it runs tests in parallel
• Assuming it generates reports

2. Which of the following is the correct syntax to parameterize a test function with two sets of inputs ("user1", "pass1") and ("user2", "pass2") in pytest?

easy

A. @pytest.parametrize('username', ['user1', 'user2'], 'password', ['pass1', 'pass2'])

B. @pytest.mark.parametrize('username, password', [('user1', 'pass1'), ('user2', 'pass2')])

C. @pytest.mark.parametrize(['username', 'password'], 'user1', 'pass1', 'user2', 'pass2')

D. @pytest.mark.parametrized('username', 'password', [('user1', 'pass1'), ('user2', 'pass2')])

Solution

1. Step 1: Recall correct decorator syntax

   The correct syntax uses @pytest.mark.parametrize with a string of parameter names and a list of tuples for values.

2. Step 2: Identify correct option

   @pytest.mark.parametrize('username, password', [('user1', 'pass1'), ('user2', 'pass2')]) matches the correct syntax exactly. Other options have wrong method names or argument formats.

3. Final Answer:

   @pytest.mark.parametrize('username, password', [('user1', 'pass1'), ('user2', 'pass2')]) -> Option B

4. Quick Check:

   Parametrize('params', [tuples]) = correct syntax [OK]

Hint: Use string param names and list of tuples for values [OK]

Common Mistakes:

• Misspelling 'parametrize' as 'parametrized' or 'parametrize'
• Passing parameters as separate lists instead of tuples
• Using wrong decorator name

3. Given the following test code, what will be the output when running the test?

import pytest

@pytest.mark.parametrize('num, expected', [(1, 2), (3, 4)])
def test_increment(num, expected):
    assert num + 1 == expected

medium

A. First test fails, second test passes

B. Both tests fail

C. First test passes, second test fails

D. Both tests pass

Solution

1. Step 1: Analyze each test case

   For (1, 2): 1 + 1 = 2, assertion passes. For (3, 4): 3 + 1 = 4, assertion passes.

2. Step 2: Determine overall result

   Since both assertions pass, both tests pass successfully.

3. Final Answer:

   Both tests pass -> Option D

4. Quick Check:

   num+1 == expected for all inputs [OK]

Hint: Check each input pair separately for assertion [OK]

Common Mistakes:

• Assuming one test fails without checking values
• Confusing expected values with actual calculation
• Ignoring that both inputs are tested

4. Identify the error in the following parameterized test code:

import pytest

@pytest.mark.parametrize('username, password')
def test_login(username, password):
    assert username != '' and password != ''

medium

A. Missing list of parameter values in @pytest.mark.parametrize decorator

B. Function parameters do not match decorator parameters

C. Assertion logic is incorrect

D. pytest module is not imported

Solution

1. Step 1: Check decorator usage

   The decorator @pytest.mark.parametrize requires two arguments: parameter names and a list of values. Here, the list of values is missing.

2. Step 2: Verify other parts

   Function parameters match decorator names, assertion logic is valid, and pytest is imported correctly.

3. Final Answer:

   Missing list of parameter values in @pytest.mark.parametrize decorator -> Option A

4. Quick Check:

   Parametrize needs names and values [OK]

Hint: Always provide parameter values list with parametrize [OK]

Common Mistakes:

• Forgetting the list of test data tuples
• Mismatching parameter names and function arguments
• Incorrect assertion logic

5. You want to test a login form with multiple username and password pairs using Selenium and pytest. Which approach correctly applies parameterization and Selenium WebDriver usage together?

hard

A. Use @pytest.mark.parametrize to pass username and password, then inside the test open the browser, enter credentials, and assert login success

B. Write separate test functions for each username and password pair without parameterization

C. Use a loop inside a single test function to iterate over username and password pairs without parameterization

D. Use @pytest.mark.parametrize but open the browser only once outside the test function

Solution

1. Step 1: Understand parameterization with Selenium

   Parameterization with @pytest.mark.parametrize allows running the test multiple times with different data, opening the browser fresh each time ensures test isolation.

2. Step 2: Evaluate other options

   Writing separate tests duplicates code, looping inside one test loses pytest reporting benefits, and opening browser only once risks test interference.

3. Final Answer:

   Use @pytest.mark.parametrize to pass username and password, then inside the test open the browser, enter credentials, and assert login success -> Option A

4. Quick Check:

   Parametrize + fresh browser per test = best practice [OK]

Hint: Parametrize inputs and open browser inside test for isolation [OK]

Common Mistakes:

• Opening browser once for all tests causing state issues
• Not using parameterize and duplicating test code
• Using loops inside tests instead of parameterize