On 2014-12-18 5:28 PM, Nils Ohlmeier wrote:
On Dec 17, 2014, at 11:47 PM, Daniel Holbert <dholb...@mozilla.com> wrote:
In contrast, your scenario is:
- We're expecting that an event *will* fire.
- We wait a bit to see if it fires.
- Fail if it the event *does not* fire before the timeout expires.
Here, failures are iffy - they may or may not be "real" depending on
delays and whether the timeout was long enough. This is precisely the
sort of thing that results in random-oranges (when e.g. new
test-platforms are added that are way slower than the system that the
test was developed on).
So, the idea now is that there should be a high threshold for adding the
second sort of test (ideally, we should just be using an event-listener
where possible).
Well there is an event listener waiting for the event to fire.
But how else then through a timeout, obviously with a high timeout value like
30 or 60 seconds, can your test tell/complain that the event is missing?
The API’s usually do not provide event listeners for NOT firing events.
mochitest already has a per-test timeout value which will mark the test
as failed in that case. You do not need to roll your own timer on top
of it.
Sure I can print an info message that my test is now waiting for an event to
pop,
but lots of my tests don’t just sit there and wait, they proceed and do other
things,
but eventually they have to block on waiting for the event callback.
In that scenario only the over all timeout will terminate my test. And somewhere
far up in the log I might find a log message. But as I tried to describe in my
other
email having a long living timer which pops complaining that event X is missing
I think is a legit use case for setTimeout in test.
If you have several async operations you need to wait on, here is the
proper way of doing things:
var gRemainingTests = 10; // the number of async ops you're waiting on
function asyncOpFinished() {
if (--gRemainingTests == 0) {
SimpleTest.finish(); // we're done
}
}
// Now, call asyncOpFinished() in the event handler for each of those
async ops.
If you need to make sure you only get one of a specific type of event,
you can maintain one counter per event type, set the initial value to 1,
and check all values for being zero before calling finish().
HTH,
Ehsan
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