Test::More/Test::Builder work VERY hard to ensure nothing inside them
alters $! or $@. This is for thing like this:
ok(do_something_scary());
> is($!, 0, "expected $! val");
> is($@, undef, '$@ not changed');
Without Test::More/Builder being careful to support this, the second 2
assertions could fail because something inside ok() modifies $! or $@.
*I cannot change Test::Builder/More* they must continue to protect $! and
$@, otherwise things break (I have a few downstream samples to show that it
does).
However. It is easy enough to have Test::Builder/More protect $! and $@
without requiring Test2 to do so.
Since Test2 is new, and nothing depends on any of its behaviors yet, I am
considering having Test2 not care about modifying $! and $@. So far I have
been taking care to preserve $! and $@, but it does add significant
complexity (and minor, but noticeable slowdown) to Test2.
*Reasons for dropping this promise from Test2:*
- Simplifies code
- $! and $@ are altered by many many things, adding { local ... } around
all of them is a pain
- Sometimes internals you don't expect to set $! will
- Perl itself documents that you cannot depend on $! and $@ being
unchanged past the immediate line after you set it.
- Test::Builder will continue to protect $! and $@, so nothing will break
- Test2 is new, nothing depends on it preserving these
*Reasons not to drop it:*
- It is helpful to people who might not realize $! and $@ are often
altered unexpectedly.
I am asking for input in case I missed any reasons/arguments for either
side. In either case backwards compatibility will be preserved.
-Chad
