Add timer getters for returned object via setTimeout, etc.

[XadillaX]

Purpose (TL;DR) - mandatory

Background (Problem in detail)

Sometimes we want to get inner metadata (e.g. delay) of a timer. The original way is to use an undocumented map clock.timers[timer.id].

This PR is to make us can use timer.delay directly.

Solution

Add some getters in returned object bind to the original timer metadata.

[codecov[bot]]

Codecov Report

Merging #362 (f5ad14f) into master (43dc8db) will increase coverage by 0.07%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #362      +/-   ##
==========================================
+ Coverage   93.98%   94.06%   +0.07%     
==========================================
  Files           1        1              
  Lines         549      556       +7     
==========================================
+ Hits          516      523       +7     
  Misses         33       33              

Flag	Coverage Δ
unit	94.06% <100.00%> (+0.07%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/fake-timers-src.js	94.06% <100.00%> (+0.07%)	:arrow_up:

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[XadillaX]

/ping @mroderick

[XadillaX]

/ping @fatso83

[fatso83]

@XadillaX Thanks for your efforts! That being said, I am trying to keep my hands off this project and leave it to someone that has more daily interest in it (I am not even coding JS these days), so hoping @sinonjs/lolex-core can take a look at this and possibly publish a new minor version.

[benjamingr]

Fwiw I saw this but I'm not sure it's a good idea to expose this functionality 😅

Sorry for the lack of feedback and dropping the ball... I'm also with a newborn, so I don't have a ton of free time.

[XadillaX]

Fwiw I saw this but I'm not sure it's a good idea to expose this functionality

Sorry for the lack of feedback and dropping the ball... I'm also with a newborn, so I don't have a ton of free time.

Sometimes I want to check the delay value of a timer that some function to be tested just set.

[benjamingr]

Sometimes I want to check the delay value of a timer that some function to be tested just set.

Isn't checking the effect (that is, .ticking that duration and then seeing the effect happened) sufficient?

[fatso83]

Closed after lack of response

[XadillaX]

When I create a timer, I can assert its delay without ticking it.

e.g.

let timer;
if (a) {
  timer = setTimeout(() => {}, 1000);
} else {
  timer = setTimeout(() => {}, 2000);
}

[fatso83]

Hi, @XadillaX . Thanks for getting back to us!

To me, this seems like checking the implementation, not the effects of said implementation. That is usually not regarded good testing practice. You want to know if something happens after X ms through its external interface, but not how (it could be two or ten timeouts in between, but that is internal details and none of your business).

So I kind of second this:

Isn't checking the effect (that is, .ticking that duration and then seeing the effect happened) sufficient?

[XadillaX]

Hi, @XadillaX . Thanks for getting back to us!

To me, this seems like checking the implementation, not the effects of said implementation. That is usually not regarded good testing practice. You want to know if something happens after X ms through its external interface, but not how (it could be two or ten timeouts in between, but that is internal details and none of your business).

So I kind of second this:

Isn't checking the effect (that is, .ticking that duration and then seeing the effect happened) sufficient?

The example may not be very clear.

Let's set a certain timer (with same callback), but in different delays.

class Checker {
  constructor() {
    this.timer = null;
    this.checked = false;
  }

  check() {
    const time = Date.now();
    this.timer = setTimeout(doCheck.bind(this), 1000 - (time % 1000));
  }

  doCheck() {
    this.checked = true;
  }
}

const checker = new Checker();
checker.check();
const now = Date.now();
assert((checker.timer.delay + now) % 1000 === 0);

// do other tests to test checker.checked