t-reftable-record: add ref tests for reftable_record_is_deletion()

reftable_record_is_deletion() is a function defined in
reftable/record.{c, h} that determines whether a record is of
type deletion or not. In the current testing setup, this function
is left untested for all the four record types (ref, log, obj, index).

Add tests for this function in the case of ref records.

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

Author: Chandra Pratap

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

@@ -102,6 +102,7 @@ static void t_reftable_ref_record_roundtrip(void)
 	for (int i = REFTABLE_REF_DELETION; i < REFTABLE_NR_REF_VALUETYPES; i++) {
 		struct reftable_record in = {
 			.type = BLOCK_TYPE_REF,
+			.u.ref.value_type = i,
 		};
 		struct reftable_record out = { .type = BLOCK_TYPE_REF };
 		struct strbuf key = STRBUF_INIT;
@@ -132,6 +133,7 @@ static void t_reftable_ref_record_roundtrip(void)
 		t_copy(&in);
 
 		check_int(reftable_record_val_type(&in), ==, i);
+		check_int(reftable_record_is_deletion(&in), ==, i == REFTABLE_REF_DELETION);
 
 		reftable_record_key(&in, &key);
 		n = reftable_record_encode(&in, dest, GIT_SHA1_RAWSZ);