class_docstr: Test the forward parallax function with various inputs.
docstr: Test parallax correction for clearsky case (returns NaN).
docstr_tok: ["Test","parallax","correction","for","clearsky","case","(","returns","NaN",")","."]
code: def test_get_parallax_corrected_lonlats_clearsky(self):
      """Test parallax correction for clearsky case (returns NaN)."""
      from satpy.modifiers.parallax import (
          get_parallax_corrected_lonlats,
      )
  
      sat_lat = sat_lon = 0
      lat = np.linspace(-20, 20, 25).reshape(5, 5)
      lon = np.linspace(-20, 20, 25).reshape(5, 5).T
      height = np.full((5, 5), np.nan)  # no CTH --> clearsky
      sat_alt = 35_000_000.0  # m above surface
      (corr_lon, corr_lat) = get_parallax_corrected_lonlats(
          sat_lon, sat_lat, sat_alt, lon, lat, height
      )
      # clearsky becomes NaN
      assert np.isnan(corr_lon).all()
      assert np.isnan(corr_lat).all()
  
imports: import datetime
  import logging
  import math
  import os
  import unittest.mock
  import dask.array
  import dask.config
  import numpy
  import pyorbital.tlefile
  import pyresample.kd_tree
  import pytest
  import xarray
  from pyproj import Geod
  from pyresample import create_area_def
  import satpy.resample
  from satpy.tests.utils import xfail_skyfield_unstable_numpy2
  from satpy.writers import get_enhanced_image
label_desc: Use image node_id 2 for calling the TestForwardParallax obj's underlying member method code with example usage: obj.test_get_parallax_corrected_lonlats_clearsky() without return types