lib/PublicInbox/Git.pm |  8 ++++++--
 t/git.t                | 15 +++++++++++++--

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index c6c1c80205ae8556b1ee976417c37fa2e8baa7ed..9207962bb7df6384eb2f611915dfcddfa555b4a6 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -362,8 +362,7 @@ }
 
 # same args as popen above
 sub qx {
-	my $self = shift;
-	my $fh = $self->popen(@_);
+	my $fh = popen(@_);
 	if (wantarray) {
 		local $/ = "\n";
 		my @ret = <$fh>;
@@ -375,6 +374,11 @@ 		my $ret = <$fh>;
 		close $fh; # caller should check $?
 		$ret;
 	}
+}
+
+sub date_parse {
+	my $d = $_[0]->qx('rev-parse', "--since=$_[1]");
+	substr($d, length('--max-age='), -1)
 }
 
 # check_async and cat_async may trigger the other, so ensure they're
diff --git a/t/git.t b/t/git.t
index 0c85e492db00be62f5d56dedefb8abbc951c4e78..7b950d88f4cc5c83f26393183b8918ce452ea34d 100644
--- a/t/git.t
+++ b/t/git.t
@@ -1,12 +1,11 @@
 # Copyright (C) 2015-2021 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict;
-use warnings;
 use Test::More;
 use PublicInbox::TestCommon;
 my ($dir, $for_destroy) = tmpdir();
-use PublicInbox::Spawn qw(popen_rd);
 use PublicInbox::Import;
+use POSIX qw(strftime);
 
 use_ok 'PublicInbox::Git';
 
@@ -18,6 +17,18 @@ 		"fast-import data readable (or run test at top level: $!";
 	my $rdr = { 0 => $fh };
 	xsys([qw(git fast-import --quiet)], { GIT_DIR => $dir }, $rdr);
 	is($?, 0, 'fast-import succeeded');
+}
+{
+	my $git = PublicInbox::Git->new($dir);
+	my $s = $git->date_parse('1970-01-01T00:00:00Z');
+	is($s, 0, 'parsed epoch');
+	local $ENV{TZ} = 'UTC';
+	$s = $git->date_parse('1993-10-02 01:02:09');
+	is(strftime('%Y-%m-%dT%H:%M:%SZ', gmtime($s)), '1993-10-02T01:02:09Z',
+		'round trips');
+	$s = $git->date_parse('1993-10-02');
+	is(strftime('%Y-%m-%d', gmtime($s)), '1993-10-02',
+		'round trips date-only');
 }
 
 {