t-reftable-merged: add tests for reftable_merged_table_max_update_index

reftable_merged_table_max_update_index() as defined by reftable/
merged.{c, h} returns the maximum update index in a merged table.
Since this function is currently unexercised, add tests for it.

Mentored-by: Patrick Steinhardt <[email protected]>
Mentored-by: Christian Couder <[email protected]>
Signed-off-by: Chandra Pratap <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Chandra Pratap

t/unit-tests/t-reftable-merged.c

@@ -236,6 +236,7 @@ static void t_merged_refs(void)
 	check(!err);
 	check_int(reftable_merged_table_hash_id(mt), ==, GIT_SHA1_FORMAT_ID);
 	check_int(reftable_merged_table_min_update_index(mt), ==, 1);
+	check_int(reftable_merged_table_max_update_index(mt), ==, 3);
 
 	while (len < 100) { /* cap loops/recursion. */
 		struct reftable_ref_record ref = { 0 };
@@ -365,6 +366,7 @@ static void t_merged_logs(void)
 	check(!err);
 	check_int(reftable_merged_table_hash_id(mt), ==, GIT_SHA1_FORMAT_ID);
 	check_int(reftable_merged_table_min_update_index(mt), ==, 1);
+	check_int(reftable_merged_table_max_update_index(mt), ==, 3);
 
 	while (len < 100) { /* cap loops/recursion. */
 		struct reftable_log_record log = { 0 };