class_docstr: Test the GACLAC file handler.
docstr: Test getting the channels.
code: def test_get_channel(self):
      """Test getting the channels."""
      from satpy.tests.utils import make_dataid
  
      counts = np.moveaxis(np.array([[[1, 2, 3], [4, 5, 6]]]), 0, 2)
      calib_channels = 2 * counts
      reader = _get_reader_mocked()
      reader.get_counts.return_value = counts
      reader.get_calibrated_channels.return_value = calib_channels
      fh = _get_fh_mocked(
          reader=reader,
          counts=None,
          calib_channels=None,
          chn_dict={"1": 0},
      )
  
      key = make_dataid(name="1", calibration="counts")
      # Counts
      res = fh._get_channel(key=key)
      np.testing.assert_array_equal(res, [[1, 2, 3], [4, 5, 6]])
      np.testing.assert_array_equal(fh.counts, counts)
  
      # Reflectance and Brightness Temperature
      for calib in ["reflectance", "brightness_temperature"]:
          key = make_dataid(name="1", calibration=calib)
          res = fh._get_channel(key=key)
          np.testing.assert_array_equal(res, [[2, 4, 6], [8, 10, 12]])
          np.testing.assert_array_equal(
              fh.calib_channels, calib_channels
          )
  
      # Invalid
      with pytest.raises(
          ValueError,
          match="coffee invalid value for <enum 'calibration'>",
      ):
          _ = make_dataid(name="7", calibration="coffee")
  
      # Buffering
      reader.get_counts.reset_mock()
      key = make_dataid(name="1", calibration="counts")
      fh._get_channel(key=key)
      reader.get_counts.assert_not_called()
  
      reader.get_calibrated_channels.reset_mock()
      for calib in ["reflectance", "brightness_temperature"]:
          key = make_dataid(name="1", calibration=calib)
          fh._get_channel(key)
          reader.get_calibrated_channels.assert_not_called()
  
imports: from datetime import datetime
  from unittest import TestCase, mock
  import dask.array
  import numpy
  import pytest
  import xarray
label_desc: Use image node_id 8 for calling the TestGACLACFile obj's underlying member method code with example usage: obj.test_get_channel() without return types