@Override
    public List<String> listDbNames() {
        return icebergCatalog.listAllDatabases();
    }
@Test
    public void testListDatabaseNames(@Mocked IcebergCatalog icebergCatalog) {
        new Expectations() {
            {
                icebergCatalog.listAllDatabases();
                result = Lists.newArrayList("db1", "db2");
                minTimes = 0;
            }
        };

        IcebergMetadata metadata = new IcebergMetadata(CATALOG_NAME, HDFS_ENVIRONMENT, icebergCatalog,
                Executors.newSingleThreadExecutor(), Executors.newSingleThreadExecutor(), null);
        List<String> expectResult = Lists.newArrayList("db1", "db2");
        Assert.assertEquals(expectResult, metadata.listDbNames());
    }