code: def test_pcolormesh_partially_masked():
      data = np.ma.masked_all((39, 29))
      data[0:100] = 10
  
      # Check that a partially masked data array does trigger a pcolor call.
      with mock.patch("cartopy.mpl.geoaxes.GeoAxes.pcolor") as pcolor:
          ax = plt.axes(projection=ccrs.PlateCarree())
          ax.pcolormesh(
              np.linspace(0, 360, 30), np.linspace(-90, 90, 40), data
          )
          assert pcolor.call_count == 1, (
              "pcolor should have been called " "exactly once."
          )
  
file_path: cartopy/lib/cartopy/tests/mpl/test_pseudo_color.py
imports: import io
  from unittest import mock
  import matplotlib.pyplot
  import numpy
  import cartopy.crs
label_desc: Use image node_id 1 for calling a global function with example usage: test_pcolormesh_partially_masked() without return types