Starting with Pytest for automated testing

Pytest is a powerful testing framework for Python, allowing developers to write simple, scalable, and efficient tests. Below is a guide to getting started with Pytest.

1. Installing Pytest

    # Install Pytest using pip
    pip install pytest
                        

2. Writing Your First Pytest Test

    # test_example.py

    def test_addition():
        assert 1 + 1 == 2

    def test_string():
        assert "pytest".upper() == "PYTEST"
                        

3. Running Tests

    # Run all tests
    pytest

    # Run tests with detailed output
    pytest -v

    # Run a specific test file
    pytest test_example.py
                        

4. Using Fixtures for Setup and Teardown

    import pytest

    @pytest.fixture
    def sample_data():
        return {"username": "test_user", "password": "secure123"}

    def test_login(sample_data):
        assert sample_data["username"] == "test_user"
                        

5. Parametrized Tests

    @pytest.mark.parametrize("num1, num2, expected", [
    (1, 2, 3),
    (3, 5, 8),
    (10, 20, 30)
    ])
    def test_addition(num1, num2, expected):
        assert num1 + num2 == expected
                        

6. Marking Tests (Skipping & Expected Failures)

    @pytest.mark.skip(reason="Skipping this test for now")
    def test_skip():
        assert False

    @pytest.mark.xfail(reason="Known issue")
    def test_expected_fail():
        assert False
                        

7. Capturing Logs in Tests

    import logging

    @pytest.fixture
    def log_data(caplog):
        caplog.set_level(logging.INFO)
        return caplog

    def test_logging(log_data):
        logging.info("This is a log message")
        assert "log message" in log_data.text
                        

8. Running Tests in Parallel

    # Install pytest-xdist for parallel execution
    pip install pytest-xdist

    # Run tests in parallel using 4 CPU cores
    pytest -n 4
                        

9. Generating Test Reports

    # Install pytest-html for generating test reports
    pip install pytest-html

    # Generate an HTML test report
    pytest --html=report.html
                        

10. Using Assertions Effectively

    def test_list_contains():
        data = [1, 2, 3, 4]
        assert 3 in data

    def test_string():
        message = "Hello Pytest"
        assert message.startswith("Hello")