A simple CRUD REST API built with Ruby (Sinatra) and PostgreSQL demonstrating Keploy integration for automated API testing.

• ✅ Complete CRUD operations for books management
• ✅ PostgreSQL database integration
• ✅ Docker Compose setup (app + database)
• ✅ Keploy integration for record and replay
• ✅ RESTful API design
• ✅ JSON request/response handling
• ✅ Error handling and validation

• Ruby 3.2 or higher
• PostgreSQL 15 or higher
• Bundler (gem install bundler)

• Docker (20.10 or higher)
• Docker Compose (v2.0 or higher)

• Keploy CLI (Installation Guide)
• Linux/WSL2 environment (Keploy requirement)

# Install Ruby dependencies
bundle install

# Create database
createdb booksdb

# Run initialization script
psql -d booksdb -f init.sql

cp .env.example .env
# Edit .env if needed for your local PostgreSQL configuration

bundle exec ruby app.rb

The API will be available at http://localhost:8000

curl http://localhost:8000/health
# Expected: {"status":"healthy","service":"Ruby Books API"}

docker-compose up --build

This will:

• Start a PostgreSQL container
• Build and start the Ruby application container
• Initialize the database with sample data
• Expose the API on port 8000

curl http://localhost:8000/health
# Expected: {"status":"healthy","service":"Ruby Books API"}

docker-compose down

To remove volumes as well:

docker-compose down -v

If you haven't installed Keploy yet:

curl --silent --location "https://github.com/keploy/keploy/releases/latest/download/keploy_linux_amd64.tar.gz" | tar xz -C /tmp
sudo mkdir -p /usr/local/bin && sudo mv /tmp/keploy /usr/local/bin && keploy version

Keploy will capture all API calls and database interactions:

keploy record -c "bundle exec ruby app.rb"

keploy record -c "docker-compose up" --container-name "ruby-books-app"

Open a new terminal and make some API requests:

# Get all books
curl http://localhost:8000/books

# Get a specific book
curl http://localhost:8000/books/1

# Create a new book
curl -X POST http://localhost:8000/books \
  -H "Content-Type: application/json" \
  -d '{
    "title": "The Hobbit",
    "author": "J.R.R. Tolkien",
    "isbn": "9780547928227",
    "published_year": 1937
  }'

# Update a book
curl -X PUT http://localhost:8000/books/1 \
  -H "Content-Type: application/json" \
  -d '{
    "title": "The Great Gatsby (Updated)",
    "author": "F. Scott Fitzgerald",
    "isbn": "9780743273565",
    "published_year": 1925
  }'

# Delete a book
curl -X DELETE http://localhost:8000/books/1

Keploy will automatically record these interactions as test cases.

Run the recorded test cases:

keploy test -c "bundle exec ruby app.rb" --delay 10

keploy test -c "docker-compose up" --container-name "ruby-books-app" --delay 10

Keploy will replay all recorded requests and verify the responses match the recorded ones.

GET /health

Response:

{
  "status": "healthy",
  "service": "Ruby Books API"
}

GET /books

Response:

{
  "books": [
    {
      "id": 1,
      "title": "The Great Gatsby",
      "author": "F. Scott Fitzgerald",
      "isbn": "9780743273565",
      "published_year": 1925
    }
  ],
  "count": 1
}

GET /books/:id

Response:

{
  "id": 1,
  "title": "The Great Gatsby",
  "author": "F. Scott Fitzgerald",
  "isbn": "9780743273565",
  "published_year": 1925
}

POST /books
Content-Type: application/json

{
  "title": "Book Title",
  "author": "Author Name",
  "isbn": "1234567890",
  "published_year": 2024
}

Response:

{
  "message": "Book created successfully",
  "book": {
    "id": 6,
    "title": "Book Title",
    "author": "Author Name",
    "isbn": "1234567890",
    "published_year": 2024
  }
}

PUT /books/:id
Content-Type: application/json

{
  "title": "Updated Title",
  "author": "Updated Author",
  "isbn": "1234567890",
  "published_year": 2024
}

Response:

{
  "message": "Book updated successfully",
  "book": {
    "id": 1,
    "title": "Updated Title",
    "author": "Updated Author",
    "isbn": "1234567890",
    "published_year": 2024
  }
}

DELETE /books/:id

Response:

{
  "message": "Book deleted successfully"
}

 KEPLOY RECORD MODE
───────────────────────────────────────────────
 📝 Recording API calls...
 ✅ Test case recorded: test-1
 ✅ Test case recorded: test-2
 ✅ Test case recorded: test-3
 ✅ Test case recorded: test-4
 ✅ Test case recorded: test-5
 
 Test cases saved to: ./keploy/tests

 KEPLOY TEST MODE
───────────────────────────────────────────────
 🧪 Running test cases...
 
 Test Case 1: PASSED ✅
 Test Case 2: PASSED ✅
 Test Case 3: PASSED ✅
 Test Case 4: PASSED ✅
 Test Case 5: PASSED ✅
 
 ────────────────────────────────────
 Test Summary:
   Total:   5
   Passed:  5
   Failed:  0
 ────────────────────────────────────

.
├── app.rb                 # Main application file
├── config.ru              # Rack configuration
├── Gemfile                # Ruby dependencies
├── Dockerfile             # Docker image configuration
├── docker-compose.yml     # Docker Compose setup
├── init.sql               # Database initialization script
└── README.md              # This file

If you see database connection errors:

1. Local setup: Ensure PostgreSQL is running

   sudo service postgresql status
   sudo service postgresql start

2. Docker setup: Check if containers are healthy

   docker-compose ps
   docker-compose logs postgres

If port 8000 is already in use:

1. Change the port in .env (local setup)
2. Or modify docker-compose.yml ports section (Docker setup)

1. Ensure you're running on Linux/WSL2
2. Check Keploy logs for detailed error messages
3. Try increasing the delay: --delay 15

• Keploy Documentation
• Sinatra Documentation
• PostgreSQL Documentation
• Ruby PG Gem

Contributions are welcome! Please feel free to submit a Pull Request.

This project is open source and available under the MIT License.

• Built with Keploy for automated API testing
• Uses Sinatra web framework
• Database: PostgreSQL

Happy Testing! 🎉