buildfarm windows checks / tap tests on windows

Hi,

As part of trying to make the aio branch tests on cirrus CI pass with
some tap tests I noticed that "src/tools/msvc/vcregress.pl recoverycheck"
hangs. A long phase of remote debugging later I figured out that that's
not a fault of the aio branch - it also doesn't pass on master (fixed in
[1]).

Which confused me - shouldn't the buildfarm have noticed? But it seems
that all msvc animals either don't have tap tests enabled or they
disable 'misc-checks' which in turn is what the buildfarm client uses to
trigger all the 'recovery' checks.

It seems we're not just skipping recovery, but also e.g. tap tests in
contrib, all the tests in src/test/modules/...

Andrew, what's the reason for that? Is it just that they hung at some
point? Were too slow?

On that last point: Running the tap tests on windows appears to be
*excruciatingly* slow. How does anybody develop on windows without a
mechanism to actually run tests in parallel?

I think it'd be good if vcregress.pl at least respected PROVE_FLAGS from
the environment - it can't currently be passed in for several of the
vcregress.pl tests, and it does seem to make things to be at least
somewhat less painful.

This makes it even clearer to me that we really need a builtin
testrunner that runs tests efficiently *and* debuggable on windows.

Greetings,

Andres Freund

[1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=1e6e40447115ca7b4749d7d117b81b016ee5e2c2