ok1(tdb_check(tdb, NULL, NULL) == 0);
/* Insert should succeed. */
ok1(tdb_store(tdb, key, data, TDB_INSERT) == 0);
ok1(tdb_check(tdb, NULL, NULL) == 0);
/* Second insert should fail. */
ok1(tdb_check(tdb, NULL, NULL) == 0);
/* Insert should succeed. */
ok1(tdb_store(tdb, key, data, TDB_INSERT) == 0);
ok1(tdb_check(tdb, NULL, NULL) == 0);
/* Second insert should fail. */