test: add custom index tests

test/boost/secondary_index_test.cc

@@ -708,11 +708,13 @@ SEASTAR_TEST_CASE(test_secondary_index_create_custom_index) {
         // "exceptions::invalid_request_exception: CUSTOM index requires
         // specifying the index class"
         assert_that_failed(e.execute_cql("create custom index on cf (a)"));
-        // It's also a syntax error to try to specify a "USING" without
-        // specifying CUSTOM. We expect the exception:
-        // "exceptions::invalid_request_exception: Cannot specify index class
-        // for a non-CUSTOM index"
-        assert_that_failed(e.execute_cql("create index on cf (a) using 'org.apache.cassandra.index.sasi.SASIIndex'"));
+        // This is the default syntax for specifying a custom index and we 
+        // 'support' "dummy-vector-backend". This should work.
+        e.execute_cql("create custom index on cf (a) using 'dummy-vector-backend'").get();
+        // It's not a syntax error to try to specify a "USING" without
+        // specifying CUSTOM. This should work.
+        e.execute_cql("create index on cf (a) using 'dummy-vector-backend'").get();
+
     });
 }
 

test/cqlpy/test_describe.py

@@ -477,16 +477,19 @@ def test_desc_index(cql, test_keyspace):
         has_local = is_scylla(cql)
         if has_local:
             create_idx_ab = f"CREATE INDEX ON {tbl}((a), b)"
+        create_idx_d = f"CREATE INDEX custom ON {tbl}(c) USING 'dummy-vector-backend'"
 
         cql.execute(create_idx_b)
         cql.execute(create_idx_c)
+        cql.execute(create_idx_d)
         if has_local:
             cql.execute(create_idx_ab)
 
         b_desc = cql.execute(f"DESC INDEX {test_keyspace}.{tbl_name}_b_idx").one().create_statement
         if has_local:
             ab_desc = cql.execute(f"DESC INDEX {test_keyspace}.{tbl_name}_b_idx_1").one().create_statement
         c_desc = cql.execute(f"DESC INDEX {test_keyspace}.named_index").one().create_statement
+        d_desc = cql.execute(f"DESC INDEX {test_keyspace}.custom").one().create_statement
 
         # Cassandra inserts a space between the table name and parentheses,
         # Scylla doesn't. This difference doesn't matter because both are
@@ -500,6 +503,7 @@ def test_desc_index(cql, test_keyspace):
             assert f"CREATE INDEX {tbl_name}_b_idx_1 ON {tbl}((a), b)" in ab_desc
 
         assert f"CREATE INDEX named_index ON {tbl}{maybe_space}(c)" in c_desc
+        assert f"CREATE INDEX custom ON {tbl}{maybe_space}(c) USING 'dummy-vector-backend'" in d_desc
 
 def test_desc_index_on_collections(cql, test_keyspace):
     # In this test, all assertions are in form of