    def test_data_collection_map_empty(self):
        """
        target: test map() API for DataCollection 
        method: create an empty data collection and map it
        expected: return map successfully
        """
        data = []
        dc = towhee.dc(data)
        dc = dc.map(str)
        result = dc.to_list()
        assert result == data
        
        return True
target: test map() API for DataCollection
method: create an empty data collection and map it
expected: return map successfully
tests/testcases/test_data_collection.py