class_docstr: Unit test multi decorator Class
  TODO: Docstring
docstr: Unit test init mask
docstr_tok: ["Unit","test","init","mask"]
code: def test_init_mask(self):
      """
      Unit test init mask
      """
      backend = Mock()
      state = MultiDecorator(backend)
      state.init_mask([1, 2, 3])
      assert backend.init_mask.call_count == 3
  
imports: import unittest
  from unittest.mock import patch, Mock
  import numpy
  import pandas
  from shapash.explainer.multi_decorator import MultiDecorator
label_desc: Use image node_id 11 for calling the TestMultiDecorator obj's underlying member method code with example usage: obj.test_init_mask() without return types