class_docstr: Unittests for the tracker class
class_docstr_tok: ["Unittests","for","the","tracker","class"]
docstr: Checks update stores to history and totals
docstr_tok: ["Checks","update","stores","to","history","and","totals"]
code: def test_update(self):
      """Checks update stores to history and totals"""
  
      tracker = Tracker()
  
      tracker.update(a=1, b="b", c=None)
      tracker.update(a=2, b="b2", c=1)
  
      assert tracker.history == {
          "a": [1, 2],
          "b": ["b", "b2"],
          "c": [None, 1],
      }
  
      assert tracker.totals == {"a": 3, "c": 1}
  
      assert tracker.latest == {"a": 2, "b": "b2", "c": 1}
  
file_path: pennylane/tests/test_tracker.py
imports: import pytest
  import pennylane
  from pennylane import Tracker
label_desc: Use image node_id 8 for calling the TestTrackerCoreBehavior obj's underlying member method code with example usage: obj.test_update() without return types