Jest unit test for a debounce function

Question

I am trying to write a unit test for a debounce function. I\'m having a hard time thinking about it.

This is the code:

Answer 1

I like this similar version easier to have failing:

jest.useFakeTimers();
test('execute just once', () => {
    const func = jest.fn();
    const debouncedFunc = debounce(func, 500);

    // Execute for the first time
    debouncedFunc();

    // Move on the timer
    jest.advanceTimersByTime(250);
    // try to execute a 2nd time
    debouncedFunc();

    // Fast-forward time
    jest.runAllTimers();

    expect(func).toBeCalledTimes(1);
});