[erlang-questions] Testing gen_statem timers

[Micael Nussbaumer]

Hi, thank you all for your inputs. I ended up doing a trace as Raimo
suggested and it works fine
the test
<https://github.com/mnussbaumer/workforce/blob/3e2498d15ecd3ccc40f5ac982307e1a84a8aa724/test/workforce_tests.erl#L595>

I think I could also have implemented `format_status` for the gen_statem
and extract the timers tuple from it? Not sure. Regarding having an API for
it I think it could be useful since that implementation detail is opaque.

Torben, thank you sharing your lib - it looks like it can be quite handy
but in this particular case it's for a library as well and I would rather
not use a dependency, and since the timer options in the gen_statem work
great by default I would like to keep using those instead of incurring
another message to set the timer & executing a callback. I can definitively
understand the appeal of having it instead be mockable though.

For the timeouts when I wrote the module that uses these timers I added the
option of setting their value on start, so that indeed I would be able to
test the behaviour easily in terms of ms and for that part it works great.
It was just this detail that was bugging me.
On the other hand, mocking also introduces a layer of "this passes the
tests but in reality it's not being tested" correct? I'm not very familiar
with mocking in tests.

Roger, thank you so much for taking the time to extract that! So I ended up
doing the state inspection instead, I haven't used dbg yet but it looks
like it can be useful. What is the difference between using dbg instead of
the bare trace?
I guess now by looking at your example that indeed I could have done the
same approach by tracing the timer sets/cancels instead of tracing the call
functions and extracting the state, that is probably cleaner.

Raimo, I replied to you by accident privately when using the list web gui -
I thought it was going to the "thread" as a reply to you. And yes, perhaps
on the sys:get_status it could include by default/on option also an element
for the timers? I did in fact try calling that at some point after your
first reply:

{data,[{"Status",running},

                 {"Parent",<0.86.0>},

                 {"Logged Events",[]},

                 {"Postponed",[]}]},

Anyway, thank you all, great reading your replies,

Micael
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