runAllAsync and runToLastAsync do not run code in the microtask queue about fake-timers

[benjamingr]

Jest can do it because it transpiles (probably)

We can't do it because queueMicrotask isn't hookable from JS like nextTick, we can use an internal Node API but without connecting a debugger it'd be hard to write it in a stable way

[fatso83]

We can't do it because queueMicrotask isn't hookable from JS like nextTick, we can use an internal Node API but without connecting a debugger it'd be hard to write it in a stable way

@benjamingr Could you elaborate on this a bit? I am not sure I understand at all. We do take control over queueMicrotask, delegating to clock.nextTick(), so after looking a bit at the code and throwing in some debugging I thought this was just about some bug in our implementation.

I see the clock.jobs array is not cleared. Rather it is doubled up before exiting:

after [
  { func: [Function (anonymous)], args: [], error: null },
  { func: [Function: afterWriteTick], args: [ [Object] ], error: null }
]

I am not quite sure why that second job is there, but you say there is something about the async versions we cannot control?

[fatso83]

I made a go and I think I found the bug, unless I am missing something substantial. This little diff should be sufficient to get the runAllAsync test working (at least when I tried):

@@ -1578,6 +1578,8 @@ function withGlobal(_global) {
                     function doRun() {
                         originalSetTimeout(function () {
                             try {
+                                runJobs(clock);
+
                                 let numTimers;
                                 if (i < clock.loopLimit) {
                                     if (!clock.timers) {

I cannot claim that I understand all the minute details of fake-timers, but I did see that runJobs, which runs the micro tasks, were missing from the runAllAsync method.

I still see that the clock.jobs array is non-empty (containing that { func: [Function: afterWriteTick] ..} job after the test has completed), but functionally everything seems to be working. Could you explain what this is, @benjamingr ?

[fatso83]

Fix in #485. I'll move the tests into the right places if I got it right 😄

[SimenB]

Closed by ^