+#!perl -w
+# Copyright (C) 2020 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use Test::More;
+use_ok 'PublicInbox::IdxStack';
+my $oid_a = '03c21563cf15c241687966b5b2a3f37cdc193316';
+my $oid_b = '963caad026055ab9bcbe3ee9550247f9d8840feb';
+
+my $stk = PublicInbox::IdxStack->new;
+is($stk->read_prepare, $stk, 'nothing');
+is($stk->num_records, 0, 'no records');
+is($stk->pop_rec, undef, 'undef on empty');
+
+$stk = PublicInbox::IdxStack->new;
+$stk->push_rec('m', 1234, 5678, $oid_a);
+is($stk->read_prepare, $stk, 'read_prepare');
+is($stk->num_records, 1, 'num_records');
+is_deeply([$stk->pop_rec], ['m', 1234, 5678, $oid_a], 'pop once');
+is($stk->pop_rec, undef, 'undef on empty');
+
+$stk = PublicInbox::IdxStack->new;
+$stk->push_rec('m', 1234, 5678, $oid_a);
+$stk->push_rec('d', 1234, 5678, $oid_b);
+is($stk->read_prepare, $stk, 'read_prepare');
+is($stk->num_records, 2, 'num_records');
+is_deeply([$stk->pop_rec], ['d', 1234, 5678, $oid_b], 'pop');
+is_deeply([$stk->pop_rec], ['m', 1234, 5678, $oid_a], 'pop-pop');
+is($stk->pop_rec, undef, 'empty');
+
+SKIP: {
+ $stk = undef;
+ my $nr = $ENV{TEST_GIT_LOG} or skip 'TEST_GIT_LOG unset', 3;
+ open my $fh, '-|', qw(git log --pretty=tformat:%at.%ct.%H), "-$nr" or
+ die "git log: $!";
+ my @expect;
+ while (<$fh>) {
+ chomp;
+ my ($at, $ct, $H) = split(/\./);
+ $stk //= PublicInbox::IdxStack->new($H);
+ # not bothering to parse blobs here, just using commit OID
+ # as a blob OID since they're the same size + format
+ $stk->push_rec('m', $at + 0, $ct + 0, $H);
+ push(@expect, [ 'm', $at, $ct, $H ]);
+ }
+ $stk or skip('nothing from git log', 3);
+ is($stk->read_prepare, $stk, 'read_prepare');
+ is($stk->num_records, scalar(@expect), 'num_records matches expected');
+ my @result;
+ while (my @tmp = $stk->pop_rec) {
+ unshift @result, \@tmp;
+ }
+ is_deeply(\@result, \@expect, 'results match expected');
+}
+
+done_testing;