Installation & Setup

Installing pytest

Getting started with pytest is straightforward. You need Python 3.7 or newer installed on your system.

pip install pytest

This installs pytest and all its core dependencies. You can verify the installation by checking the version:

pytest --version

Project Structure

A well-organized pytest project typically follows this structure:

my_project/
├── src/
│   └── my_package/
│       ├── __init__.py
│       └── calculator.py
├── tests/
│   ├── __init__.py
│   ├── conftest.py
│   └── test_calculator.py
├── pytest.ini
└── requirements.txt

Keep your source code in src/ and your tests in tests/. This separation makes it clear what is production code and what is test code.

Configuration with pytest.ini

Create a pytest.ini file in your project root to configure pytest behavior:

[pytest]
testpaths = tests
python_files = test_*.py
python_classes = Test*
python_functions = test_*
addopts = -v --tb=short

This tells pytest where to find tests and how to format output. The addopts setting applies default command-line options every time you run pytest.

Using a Virtual Environment

Always use a virtual environment to isolate your project dependencies:

# Create virtual environment
python -m venv venv

# Activate it (Windows)
venv\Scripts\activate

# Activate it (macOS/Linux)
source venv/bin/activate

# Install pytest inside the environment
pip install pytest

This prevents version conflicts between projects and keeps your system Python clean.