@Override
    public ResultSet getFunctionColumns(final String catalog, final String schemaPattern, final String functionNamePattern, final String columnNamePattern) throws SQLException {
        return createDatabaseMetaDataResultSet(getDatabaseMetaData().getFunctionColumns(getActualCatalog(catalog), getActualSchema(schemaPattern), functionNamePattern, columnNamePattern));
    }
@Test
    void assertGetFunctionColumns() throws SQLException {
        when(databaseMetaData.getFunctionColumns("test", null, null, null)).thenReturn(resultSet);
        assertThat(shardingSphereDatabaseMetaData.getFunctionColumns("test", null, null, null), instanceOf(DatabaseMetaDataResultSet.class));
    }