Run Emacs lisp tests locally

You can go to the pdf-tools folder and run make test to run the ERT tests and check if the changes you have made to the code break any of the tests.

The tests are written in ERT, which is the built-in testing system in Emacs. However, they are run using Cask which you will have to install first, if you don’t have it already. You can install Cask by following the instructions on their site at https://github.com/cask/cask