class_docstr: Test the HRITJMAFileHandler.
class_docstr_tok: ["Test","the","HRITJMAFileHandler","."]
docstr: Test conversion from modified julian day to datetime64.
docstr_tok: ["Test","conversion","from","modified","julian","day","to","datetime64","."]
code: def test_mjd2datetime64(self):
      """Test conversion from modified julian day to datetime64."""
      from satpy.readers.hrit_jma import mjd2datetime64
  
      assert mjd2datetime64(np.array([0])) == np.datetime64(
          "1858-11-17", "ns"
      )
      assert mjd2datetime64(np.array([40587.5])) == np.datetime64(
          "1970-01-01 12:00", "ns"
      )
  
imports: import unittest
  from unittest import mock
  import dask.array
  import numpy
  from xarray import DataArray
  from satpy.tests.utils import make_dataid
label_desc: Use image node_id 10 for calling the TestHRITJMAFileHandler obj's underlying member method code with example usage: obj.test_mjd2datetime64() without return types