+{
+ local $ENV{GIT_CONFIG} = '/path/to/this/better/not/exist';
+ my $fh = popen_rd([qw(env)], { GIT_CONFIG => undef });
+ ok(!grep(/^GIT_CONFIG=/, <$fh>), 'GIT_CONFIG clobbered');
+}
+
+{ # ->CLOSE vs ->DESTROY waitpid caller distinction
+ my @c;
+ my $fh = popen_rd(['true'], undef, { cb_arg => [sub { @c = caller }] });
+ ok(close($fh), '->CLOSE fired and successful');
+ ok(scalar(@c), 'callback fired by ->CLOSE');
+ ok(grep(!m[/PublicInbox/DS\.pm\z], @c), 'callback not invoked by DS');
+
+ @c = ();
+ $fh = popen_rd(['true'], undef, { cb_arg => [sub { @c = caller }] });
+ undef $fh; # ->DESTROY
+ ok(scalar(@c), 'callback fired by ->DESTROY');
+ ok(grep(!m[/PublicInbox/ProcessPipe\.pm\z], @c),
+ 'callback not invoked by ProcessPipe');
+}
+
+{ # children don't wait on siblings
+ use POSIX qw(_exit);
+ pipe(my ($r, $w)) or BAIL_OUT $!;
+ my @arg;
+ my $cb = [ sub { @arg = @_; warn "x=$$\n" }, 'hi' ];
+ my $fh = popen_rd(['cat'], undef, { 0 => $r, cb_arg => $cb });
+ my $pp = tied *$fh;
+ my $pid = fork // BAIL_OUT $!;
+ local $SIG{__WARN__} = sub { _exit(1) };
+ if ($pid == 0) {
+ local $SIG{__DIE__} = sub { _exit(2) };
+ undef $fh;
+ _exit(0);
+ }
+ waitpid($pid, 0);
+ is($?, 0, 'forked process exited');
+ my @w;
+ local $SIG{__WARN__} = sub { push @w, @_ };
+ close $w;
+ close $fh;
+ is($?, 0, 'cat exited');
+ is(scalar(@arg), 2, 'callback got args');
+ is($arg[1], 'hi', 'passed arg');
+ like($arg[0], qr/\A\d+\z/, 'PID');
+ is_deeply(\@w, [ "x=$$\n" ], 'callback fired from owner');
+}
+