faker

https://github.com/stympy/faker

Ruby

A library for generating fake data such as names, addresses, and phone numbers.

Faker::Code.isbn

By default generates 10 sign isbn code in format 123456789-X
You can pass 13 to generate new 13 sign code

Source | Google | Stack overflow

Edit

git clone [email protected]:stympy/faker.git
cd faker
open lib/faker/default/code.rb

Contribute

# Make a new branch
git checkout -b -your-name--update-docs-Faker--Code-isbn-for-pr

# Commit to git
git add lib/faker/default/code.rbgit commit -m "better docs for Faker::Code.isbn"

# Open pull request
gem install hub # on a mac you can `brew install hub`
hub fork
git push <your name> -your-name--update-docs-Faker--Code-isbn-for-pr
hub pull-request

# Celebrate!