Events must be tested like any other runnable code in a project.
The candidates will be evaluated by:
Mocking the firing and processing of events allows the code to be easily tested locally. It puts the test in a format (unit tests) where they can be run in the existing framework using GitHub Actions on GitHub. It does not change the existing procedure of testing the code. It is also free of charge when using the free version of GitHub Actions (see testing automation).
The testing on a live server would require a running dedicated and managed server. Production wants to implement such a server soon, but every developer might want to test their code locally so immediately see what is wrong with the code. Deploying a test build on the server does not fit into the existing testing solution of using GitHub Actions. The server costs money to run and maintain.
Using GitHub Actions is suitable for this project. It will also be more elegant to integrate this solution into the final build pipeline, because the testing step is clearly defined and done.