class_docstr: Test VIIRS SDR Reader.
class_docstr_tok: ["Test","VIIRS","SDR","Reader","."]
docstr: Load DNB dataset with no provided scale factors.
code: def test_load_dnb_no_factors(self):
      """Load DNB dataset with no provided scale factors."""
      from satpy.readers import load_reader
  
      r = load_reader(self.reader_configs)
      loadables = r.select_files_from_pathnames(
          [
              "SVDNB_npp_d20120225_t1801245_e1802487_b01708_c20120226002130255476_noaa_ops.h5",
              "GDNBO_npp_d20120225_t1801245_e1802487_b01708_c20120226002130255476_noaa_ops.h5",
          ]
      )
      r.create_filehandlers(loadables, {"include_factors": False})
      ds = r.load(["DNB"])
      assert len(ds) == 1
      for d in ds.values():
          data = d.values
          # no scale factors, default factor 1 and offset 0
          # multiply DNB by 10000 should mean the first value of 0 should be:
          # data * factor * 10000 + offset * 10000
          # 0 * 1 * 10000 + 0 * 10000 => 0
          assert data[0, 0] == 0
          # the second value of 1 should be:
          # 1 * 1 * 10000 + 0 * 10000 => 10000
          assert data[0, 1] == 10000
          self._assert_dnb_radiance_properties(d, with_area=True)
  
imports: import os
  import unittest
  from contextlib import contextmanager
  from unittest import mock
  import numpy
  import pytest
  from satpy.readers.viirs_atms_sdr_base import DATASET_KEYS
  from satpy.tests.reader_tests.test_hdf5_utils import FakeHDF5FileHandler
label_desc: Use image node_id 20 for calling the TestVIIRSSDRReader obj's underlying member method code with example usage: obj.test_load_dnb_no_factors() without return types