class_docstr: Testing the file handler.
class_docstr_tok: ["Testing","the","file","handler","."]
docstr: Test VIS calibration.
code: def test_calibrate_vis(self):
      """Test VIS calibration."""
      rad = xr.DataArray([0, 1, 10, 100, 500])
      refl_expected = xr.DataArray(
          [0.0, 0.188852, 1.88852, 18.8852, 94.426]
      )
      refl = self.reader._calibrate_vis(
          radiance=rad, k=self.coefs["00_7"]["k"]
      )
      assert np.allclose(
          refl.data, refl_expected.data, atol=1e-06
      ), "Incorrect conversion from radiance to reflectance"
  
imports: import datetime
  import unittest
  from unittest import mock
  import numpy
  import pytest
  import xarray
  from pyresample.geometry import AreaDefinition
  from satpy.readers.goes_imager_nc import is_vis_channel
  from satpy.tests.utils import make_dataid
label_desc: Use image node_id 6 for calling the GOESNCBaseFileHandlerTest obj's underlying member method code with example usage: obj.test_calibrate_vis() without return types