ref-filter: add tests for deltabase

Test new formatting option deltabase.

Signed-off-by: Olga Telezhnaia <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: telezhnaya

t/t6300-for-each-ref.sh

@@ -84,6 +84,7 @@ test_atom head push:strip=-1 master
 test_atom head objecttype commit
 test_atom head objectsize 171
 test_atom head objectsize:disk 138
+test_atom head deltabase 0000000000000000000000000000000000000000
 test_atom head objectname $(git rev-parse refs/heads/master)
 test_atom head objectname:short $(git rev-parse --short refs/heads/master)
 test_atom head objectname:short=1 $(git rev-parse --short=1 refs/heads/master)
@@ -127,6 +128,8 @@ test_atom tag objecttype tag
 test_atom tag objectsize 154
 test_atom tag objectsize:disk 138
 test_atom tag '*objectsize:disk' 138
+test_atom tag deltabase 0000000000000000000000000000000000000000
+test_atom tag '*deltabase' 0000000000000000000000000000000000000000
 test_atom tag objectname $(git rev-parse refs/tags/testtag)
 test_atom tag objectname:short $(git rev-parse --short refs/tags/testtag)
 test_atom head objectname:short=1 $(git rev-parse --short=1 refs/heads/master)