Promise fulfilled delay failures

[kitsonk]

We are routinely getting something like the following. We need to figure out if the test is just being temperamental or if there is some problem we are regularly overrunning this timeout:

× firefox on Windows 10 - unit tests - async/timing - delay() - resolves a promise after the given timeout (0.465s)
AssertionError: expected 462 to be close to 250 +/- 25
  at AssertionError  <__intern/node_modules/chai/chai.js:4760:18>
  at [2]</module.exports/Assertion.prototype.assert  <__intern/node_modules/chai/chai.js:203:1>
  at [4]</module.exports/<  <__intern/node_modules/chai/chai.js:1727:1>
  at [9]</module.exports/ctx[name]  <__intern/node_modules/chai/chai.js:3475:18>
  at [5]</module.exports/assert.closeTo  <__intern/node_modules/chai/chai.js:2968:5>
  at ["delay()"]["resolves a promise after the given timeout"]/<  <_build/tests/unit/async/timing.js:21:21>

[mwistrand]

Given how setTimeout is scheduled, this isn't surprising in slower environments (e.g., a VM) with many tests being run together. I'm in the process of figuring out a margin that works better for this test.

[kitsonk]

Yeah, I seem to be getting inconsistent results, based on browser and testing provider. BrowserStack fail on some combinations, SauceLabs fails on a different set. I think in particular the test should have a wider range... The delay should never be faster but can obviously be significantly longer than specified in delay().

[kitsonk]

Seems like there are a few other things that are causing issues... On Sauce it seems like Firefox is pretty "slow".