Sometimes load causes the VM to run more slowly, especially with
parallel tests. This change allows the wait block a little extra wiggle
room to account for that. Ending early is still tested with a fairly
strict threshold.
Newer versions of `tap` run more asynchronously, so sometimes using `process.nextTick(process.exit)`
to end a test would prevent the test from completing correctly. Removing all instances of
`process.nextTick(process.exit)` put tests into three categories:
* the test still worked correctly -- no fixup needed.
* the test would hang because the VM's `_steppingInterval` was keeping
Node alive. These tests call a new `quit()` method which ends the
stepping interval.
* the `load-extensions` test needed special attention because the "Video
Sensing" extension starts its own loop using `setTimeout`. I added a
`_stopLoop()` method on the extension and directly call that from the
test. I'm not completely happy with this solution but anything more
general would likely require a change to the extension spec, so I'm
leaving that as a followup task.
As part of simplifying the CI setup I plan to not explicitly specify
`--jobs=4` to `tap` going forward. Upgrading to a newer version of `tap`
means that it will automatically parallelize jobs according to available
CPU count, which should be better anyway. Only one of our tests was
incompatible with newer versions of `tap`, so this commit includes a
compatibility fix there.
Also, by default newer versions of `tap` calculate coverage and consider
the test run to fail if below the configured thresholds. The default is
100% coverage and we're not there, so I adjusted the thresholds to match
where we're at for now. We can ratchet those up over time.
- Add pointer member to thread. This is the current executing block.
- Add stackFrame member to thread. This is the current frame
information like procedure parameters.
This is a step potentially towards stack-less threads. With further
modifications we could have stack and stackFrames be null if a script
does not call a procedure.
