@Override
    public List<String> listDbNames() {
        return ImmutableList.<String>builder()
                .addAll(this.normal.listDbNames())
                .addAll(this.informationSchema.listDbNames())
                .build();
    }
@Test
    void testListDbNames(@Mocked ConnectorMetadata connectorMetadata) {
        new Expectations() {
            {
                connectorMetadata.listDbNames();
                result = ImmutableList.of("test_db1", "test_db2");
                times = 1;
            }
        };

        CatalogConnectorMetadata catalogConnectorMetadata = new CatalogConnectorMetadata(
                connectorMetadata,
                informationSchemaMetadata,
                metaMetadata
        );

        List<String> dbNames = catalogConnectorMetadata.listDbNames();
        List<String> expected = ImmutableList.of("test_db1", "test_db2", InfoSchemaDb.DATABASE_NAME);
        assertEquals(expected, dbNames);
    }