reftable_log_record_compare_key() is a function defined by
reftable/record.{c, h} and is used to compare the keys of two
log records when sorting multiple log records using 'qsort'.
In the current testing setup, this function is left unexercised.
Add a testing function for the same.

Mentored-by: Patrick Steinhardt [off-list ref]
Mentored-by: Christian Couder [off-list ref]
Signed-off-by: Chandra Pratap <redacted>
---
 t/unit-tests/t-reftable-record.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/t/unit-tests/t-reftable-record.c b/t/unit-tests/t-reftable-record.c
index b949617c88..d480cc438a 100644
--- a/t/unit-tests/t-reftable-record.c
+++ b/t/unit-tests/t-reftable-record.c

@@ -214,6 +214,30 @@ static void test_reftable_log_record_comparison(void)
 		reftable_record_release(&in[i]);
 }

+static void test_reftable_log_record_compare_key(void)
+{
+	struct reftable_log_record logs[14] = { 0 };
+	size_t N = ARRAY_SIZE(logs), i;
+
+	for (i = 0; i < N; i++) {
+		if (i < N / 2) {
+			logs[i].refname = xstrfmt("%02"PRIuMAX, (uintmax_t)i);
+			logs[i].update_index = i;
+		} else {
+			logs[i].refname = xstrdup("refs/heads/master");
+			logs[i].update_index = i;
+		}
+	}
+
+	QSORT(logs, N, reftable_log_record_compare_key);
+
+	for (i = 1; i < N; i++)
+		check(reftable_log_record_compare_key(&logs[i - 1], &logs[i]) < 0);
+
+	for (i = 0; i < N; i++)
+		reftable_log_record_release(&logs[i]);
+}
+

 static void test_reftable_log_record_roundtrip(void)
 {
 	struct reftable_log_record in[] = {

@@ -519,6 +543,7 @@ int cmd_main(int argc, const char *argv[])
 	TEST(test_reftable_index_record_comparison(), "comparison operations work on index record");
 	TEST(test_reftable_obj_record_comparison(), "comparison operations work on obj record");
 	TEST(test_reftable_ref_record_compare_name(), "reftable_ref_record_compare_name works");
+	TEST(test_reftable_log_record_compare_key(), "reftable_log_record_compare_key works");
 	TEST(test_reftable_log_record_roundtrip(), "record operations work on log record");
 	TEST(test_reftable_ref_record_roundtrip(), "record operations work on ref record");
 	TEST(test_varint_roundtrip(), "put_var_int and get_var_int work");
--

2.45.2.404.g9eaef5822c