code: def test_plot_map_empty():
      # Test that things don't crash when we give a map with nothing above
      # threshold
      # This is only a smoke test
      mpl.use("svg")
      import matplotlib.pyplot as pl
  
      plt.switch_backend("svg")
      data = np.zeros((20, 20, 20))
      plot_anat(data, mni_sform)
      plot_map(data, mni_sform, slicer="y", threshold=1)
      plt.close("all")
  
file_path: nipy/nipy/labs/viz_tools/test/test_activation_maps.py
imports: import tempfile
  import numpy
  import pytest
  from unittest.mock import patch
  from ..activation_maps import demo_plot_map, plot_anat, plot_map
  from ..anat_cache import _AnatCache, mni_sform
label_desc: Use image node_id 5 for calling a global function with example usage: test_plot_map_empty() without return types