code: def test_available(self):
      if _available:
          self.assertTrue(extensions.PlotReport.available())
      else:
          # It shows warning only when matplotlib is not available
          with pytest.warns(UserWarning):
              self.assertFalse(extensions.PlotReport.available())
  
file_path: chainer/tests/chainer_tests/training_tests/extensions_tests/test_plot_report.py
imports: import unittest
  import warnings
  import pytest
  from chainer import testing
  from chainer.training import extensions
label_desc: Use image node_id 1 for calling the TestPlotReport obj's underlying member method code with example usage: obj.test_available() without return types