code: def test_LongitudeFormatter_degree_symbol():
      formatter = LongitudeFormatter(
          degree_symbol="", dateline_direction_label=True
      )
      p = ccrs.PlateCarree()
      formatter.set_axis(Mock(axes=Mock(GeoAxes, projection=p)))
      test_ticks = [-180, -120, -60, 0, 60, 120, 180]
      result = [formatter(tick) for tick in test_ticks]
      expected = ["180W", "120W", "60W", "0", "60E", "120E", "180E"]
      assert result == expected
  
imports: from unittest.mock import Mock
  import matplotlib.pyplot
  import numpy
  import pytest
  import cartopy.crs
  from cartopy.mpl.geoaxes import GeoAxes
  from cartopy.mpl.ticker import LatitudeFormatter, LatitudeLocator, LongitudeFormatter, LongitudeLocator
label_desc: Use image node_id 10 for calling a global function with example usage: test_LongitudeFormatter_degree_symbol() without return types