Tracking function execution time with jasmine

Question

Is it possible to create a reusable jasmine matcher that would assert a function to run for less than N seconds?

Sample expectation style:

expect(someFunction, [arg1, arg2]).toBeCompletedForLessThan(3);
expect(obj.someMethod, [arg1, arg2]).toBeCompletedForLessThan(5);

---

We'd like to tie this up with Protractor and custom performance tests where we want to assert that certain UI execution steps don't go beyond the time limit.

Answer 1

I would measure the elapsed time with a custom timer and then assert the result with .toBeLessThan:

var timer = Timer();

$("#mytext").getText().then(function(text){
    console.log(text);
});

expect(timer.elapsed).toBeLessThan(1000);   // to be under 1 second

The timer:

var Timer = function() {
  var starttime = 0;

  browser.controlFlow().execute(function() {
    starttime = Date.now()
  });

  return {
    get elapsed() {
      return browser.controlFlow().execute(() => Date.now() - starttime);
    }
  };
};