🧪 Test-Driven Development (TDD) Lab

📌 Overview

This lab focuses on Test-Driven Development (TDD)—writing test cases first and then implementing the required functionality. Each student will contribute one test case and submit a pull request.

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📂 Project Structure

The repository is organized as follows:

tdd_lab/
├── 📂 tests/                   # Contains all test cases
│   ├── 📄 test_counter.py       # Test cases for the counter API (each student contributes a test)
├── 📂 src/                      # Source code for the counter service
│   ├── 📄 __init__.py           # Flask app initialization
│   ├── 📄 counter.py            # Counter API implementation
│   ├── 📄 status.py             # HTTP status codes
├── 📄 requirements.txt          # Dependencies for the project
├── 📄 pytest.ini                # Pytest configuration
├── 📄 README.md                 # Project documentation

Python Version(s)

To follow this lab, you need Python version 3.8 or later. The exercises have been tested with the following versions: 3.8.1, 3.9.5, 3.9.6, 3.9.7, and 3.10.10. However, any Python version 3.8+ should work without configuration issues.

If you encounter any setup or configuration problems, please reach out to the T.A. for assistance.

1. Upgrading PIP:

Sometimes it is useful to upgrade pip before installing dependencies. If you like, run: pip install --upgrade pip and later install the dependencies using: pip install -r requirements.txt

2. Create a Virtual Environment (Highly Recommended)

• It is a good practice to configure python virtual environment. Use the commands below to setup python virtual environment on Linux/MacOS or Windows OS

  python3 -m venv venv
  source venv/bin/activate  # macOS/Linux
  venv\Scripts\activate     # Windows

3. Install Dependencies

pip install -r requirements.txt

4. Set Flask Environment Variable

• macOS/Linux

   export FLASK_APP=src

• Windows

    set FLASK_APP=src

5. Run Flask Locally to Ensure API Works

flask run

✅ Visit http://127.0.0.1:5000/counters/foo in the browser. If it returns {"error": "Counter not found"}, your API is working!

6. Merge Conflicts

If you are having trouble merging changes to the main branch of the team's repo, you can take a look at this doc: How to Handle Merge Conflicts in the Testing Lab.

7. 🛠️ Troubleshooting Guide

Below are common errors students may encounter and their solutions:

Error	Cause	Solution
ImportError: cannot import name 'app' from 'src'	Flask app is not detected	Run export FLASK_APP=src before running flask run
Error: No such command 'db'	Flask-Migrate missing	Run pip install flask-migrate
sqlalchemy.exc.OperationalError: table account has no column named balance	Database not migrated	Run flask db upgrade
ModuleNotFoundError: No module named 'src'	Missing dependencies	Run pip install -r requirements.txt

If you continue to experience issues, follow these steps:

1. Check that Flask is running with flask run.
2. Ensure all dependencies are installed with pip install -r requirements.txt.
3. Consult your team first before reaching out for help.
4. If the issue persists, open a GitHub Issue in your team repository, including:
   • A clear description of the problem.
   • The exact error message.
   • Steps you have already tried.

🚀 Debug first, then ask for help!