python-interview / TodoAPI

This is a simple Todo List API built with FastAPI and Python 3.13+. This project is currently being used for Python full-stack candidates.

Features

• FastAPI - Modern, fast web framework for building APIs
• Python 3.13+ - Latest Python with full type hints
• Pydantic v2 - Data validation using Python type annotations
• In-memory storage - Simple data persistence (resets on restart)
• Poetry - Modern dependency management
• pytest - Comprehensive unit tests with mocking
• Ruff - Extremely fast Python linter and formatter
• mypy - Static type checker with strict mode
• DevContainer - VS Code development container support

Prerequisites

• Python 3.13+ or Docker with VS Code DevContainer support
• Poetry (if running locally without Docker)

Installation

Using Poetry (Local)

# Install Poetry if you haven't already
curl -sSL https://install.python-poetry.org | python3 -

# Install dependencies
poetry install

# Activate virtual environment
poetry shell

Using DevContainer (Recommended)

1. Open the project in VS Code
2. Install the "Dev Containers" extension
3. Press F1 and select "Dev Containers: Reopen in Container"
4. Dependencies will be installed automatically

Running the app

Development mode with hot reload

# Using Poetry
poetry run uvicorn app.main:app --reload --host 0.0.0.0 --port 8000

# Or if inside poetry shell
uvicorn app.main:app --reload --host 0.0.0.0 --port 8000

Production mode

poetry run uvicorn app.main:app --host 0.0.0.0 --port 8000

The API will be available at:

• API: http://localhost:8000
• Interactive API docs (Swagger): http://localhost:8000/docs
• Alternative API docs (ReDoc): http://localhost:8000/redoc

API Endpoints

All endpoints are prefixed with /api/todolists:

Method	Endpoint	Description
GET	/api/todolists	Get all todo lists
GET	/api/todolists/{id}	Get a specific todo list
POST	/api/todolists	Create a new todo list
PUT	/api/todolists/{id}	Update an existing todo list
DELETE	/api/todolists/{id}	Delete a todo list

Testing

# Run all tests
poetry run pytest

# Run tests with coverage
poetry run pytest --cov=app --cov-report=html

# Run tests in watch mode
poetry run pytest-watch

# Run tests with verbose output
poetry run pytest -v

Code Quality

Linting and Formatting with Ruff

# Check for linting errors
poetry run ruff check .

# Fix linting errors automatically
poetry run ruff check --fix .

# Format code
poetry run ruff format .

Type Checking with mypy

# Run type checker
poetry run mypy app/

# Run type checker on all files
poetry run mypy .

Project Structure

.
├── app/
│   ├── __init__.py
│   ├── main.py              # FastAPI application entry point
│   ├── models.py            # Pydantic models (schemas)
│   ├── routers/
│   │   ├── __init__.py
│   │   └── todo_lists.py    # TodoList API endpoints
│   └── services/
│       ├── __init__.py
│       └── todo_lists.py    # Business logic and in-memory storage
├── tests/
│   ├── __init__.py
│   └── test_todo_lists.py   # Unit tests for all endpoints
├── .devcontainer/           # VS Code DevContainer configuration
├── pyproject.toml           # Poetry dependencies and tool configs
├── .ruff.toml              # Ruff linter/formatter configuration
├── mypy.ini                # mypy type checker configuration
└── README.md

Development Tools

This project uses modern Python development tools:

• Poetry: Dependency management and packaging
• Ruff: Extremely fast linter and formatter (replaces Black, isort, flake8)
• mypy: Static type checker with strict mode enabled
• pytest: Testing framework with async support
• httpx: HTTP client for testing FastAPI endpoints

In-Memory Storage

This application uses in-memory storage (Python lists/dicts). Data will be lost when the application restarts. This is intentional for simplicity and is suitable for interview/demo purposes.

Check integration tests at: https://github.com/crunchloop/interview-tests

Contact

• Martín Fernández (mfernandez@crunchloop.io)

About Crunchloop

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