TooLoo is Open Source and written in Raku. You can find the source code here on GitHub.
The most important thing you can do when contributing is to make sure that the bash_unit tests all pass, and that you add new ones for any new functionality.
Raku unit tests are welcomed too, but most everything TooLoo does involves database calls, which is far easier, and more reliable, to test with a real test database. Mocking and Stubbing are great techniques, but in this scenario frequently not the best answer.
To run the bash_unit tests, cd into the bash_unit_tests directory and run
bash_unit ./tooloo_test.sh
It should be noted that the ordering of the tests in tooloo_test.sh is important, as they are gradually populating the database and expecting the data from prior tests to still be present.
While bug fixes are always welcome, you should first ping us on Mastodon, or file a ticket with new feature requests before diving in to them. You are, of course, free to fork the repo and add whatever functionality you want, but we'd prefer to work together towards new features that work for everyone.
Go for it! Just make your fix, run (and maybe improve) the tests, and submit a PR. Pinging us on Mastodon may help getting it noticed and merged faster.
Same thoughts as fixing bugs. If you can simplify the code, make it more readable, make it more testable, or make it more idiomatic we'll probably want to merge those changes.