code: def test_initialisation(self):
      with self.assertRaisesRegexp(ValueError, ""):
          reader = ImageReader(["test"])
          reader.initialise(
              MULTI_MOD_DATA, MULTI_MOD_TASK, multi_mod_list
          )
      reader = ImageReader(None)
      # reader.initialise(MULTI_MOD_DATA, MULTI_MOD_TASK, multi_mod_list)
  
      reader = ImageReader(["image"])
      reader.initialise(MULTI_MOD_DATA, MULTI_MOD_TASK, multi_mod_list)
      self.assertEqual(len(reader.output_list), 4)
  
      reader = ImageReader(["image"])
      reader.initialise(
          SINGLE_MOD_DATA, SINGLE_MOD_TASK, single_mod_list
      )
      self.assertEqual(len(reader.output_list), 4)
  
      reader = ImageReader(["image"])
      with self.assertRaisesRegexp(ValueError, ""):
          reader.initialise(SINGLE_MOD_DATA, SINGLE_MOD_TASK, [])
  
imports: from __future__ import absolute_import, print_function
  import os
  import numpy
  import tensorflow
  from niftynet.io.image_reader import ImageReader
  from niftynet.io.image_sets_partitioner import ImageSetsPartitioner
  from niftynet.layer.discrete_label_normalisation import DiscreteLabelNormalisationLayer
  from niftynet.layer.pad import PadLayer
  from niftynet.utilities.util_common import ParserNamespace
  from tests.reader_modular_test import generate_2d_images, SEG_THRESHOLD
  from tests.niftynet_testcase import NiftyNetTestCase
label_desc: Use image node_id 1 for calling the ImageReaderTest obj's underlying member method code with example usage: obj.test_initialisation() without return types