To run the test, go back to your console and run the test command using your preferred package manager. It should display a report telling you that tests succeeded.
Note
The simnet object is available globally in the tests, and is automatically initialized before each test. You can have a look at the vitest.config.js file at the root of you project for more details.
Getting back to the tests - the first test checks that the increment function returns the new value and saves it to the count variable.
The second test checks that an print_event is emitted when the increment function is called.