class_docstr: Test the SCMIFileHandler's area creation.
docstr: Test the area generation for merc projection.
docstr_tok: ["Test","the","area","generation","for","merc","projection","."]
code: def test_get_area_def_merc(self, adef):
      """Test the area generation for merc projection."""
      reader = self.create_reader(
          "goes_imager_projection",
          {
              "semi_major_axis": 1.0,
              "semi_minor_axis": 1.0,
              "longitude_of_projection_origin": -90.0,
              "standard_parallel": 0.0,
              "grid_mapping_name": "mercator",
          },
      )
      reader.get_area_def(None)
  
      assert adef.call_count == 1
      call_args = tuple(adef.call_args)[0]
      assert call_args[3] == {
          "a": 1.0,
          "b": 1.0,
          "lon_0": -90.0,
          "lat_0": 0.0,
          "lat_ts": 0.0,
          "proj": "merc",
          "units": "m",
      }
      assert call_args[4] == reader.ncols
      assert call_args[5] == reader.nlines
      np.testing.assert_allclose(call_args[6], (-2.0, -2.0, 2, 2.0))
  
imports: import unittest
  from unittest import mock
  import numpy
  import pytest
  import xarray
label_desc: Use image node_id 5 for calling the TestSCMIFileHandlerArea obj's underlying member method code with example usage: obj.test_get_area_def_merc(adef) without return types