class_docstr: Unit test for DataCollection.
class_docstr_tok: ["Unit","test","for","DataCollection","."]
code: def test_normal(self):
      p = (
          pipe.input("a")
          .map("a", "b", lambda x: x + 1)
          .output("a", "b")
      )
  
      res = p(1)
      dc = DataCollection(res)
      dc.show()
  
      self.assertEqual(dc[0]["a"], 1)
      self.assertEqual(dc[0]["b"], 2)
  
file_path: towhee/tests/unittests/datacollection/test_data_collection.py
imports: import doctest
  import unittest
  import towhee.datacollection.data_collection
  from towhee.datacollection import DataCollection
  from towhee import pipe
label_desc: Use image node_id 1 for calling the TestDataCollection obj's underlying member method code with example usage: obj.test_normal() without return types