};
ok($@, 'V2Writable fails on non-existent dir');
+{
+ my $v2w = PublicInbox::V2Writable->new($tmp, 1);
+ ok($v2w, 'creat flag works');
+ $v2w->{parallel} = 0;
+ $v2w->init_inbox(0);
+ my $alt = "$tmp->{inboxdir}/all.git/objects/info/alternates";
+ open my $fh, '>>', $alt or die $!;
+ print $fh "$inboxdir/all.git/objects\n" or die $!;
+ chmod(0664, $fh) or die "fchmod: $!";
+ close $fh or die $!;
+ open $fh, '<', $alt or die $!;
+ my $before = do { local $/; <$fh> };
+
+ ok($v2w->git_init(3), 'init a new epoch');
+ open $fh, '<', $alt or die $!;
+ my $after = do { local $/; <$fh> };
+ ok(index($after, $before) > 0,
+ 'old contents preserved after adding epoch');
+ like($after, qr!\A[^\n]+?/3\.git/objects\n!s,
+ 'first line is newest epoch');
+ my $mode = (stat($alt))[2] & 07777;
+ is($mode, 0664, sprintf('0%03o', $mode).' is 0664');
+}
+
done_testing();