How to test that a function returned without doing anything

I’m writing a suite of Jest tests, and the following question came up. How can I test that a function simply returns if it receives an invalid argument? For example, I would like to test that the function changeAge below returns immediately if it receives a newAge or id that is not a whole number.

function changeAge (id, newAge) {
  const isWholeNumber = num => Number.isInteger(newAge) && newAge >= 0
  if (!isWholeNumber(id) || !isWholeNumber(newAge)) {
    return
  } 

  const person = getPerson(id)
  person.age = newAge
}

In this example, there’s no way in the test to retrieve the person data to verify whether the age property was changed.