code: def generate_test_images():
      """Generate all test images.
  
      Returns
      -------
      results: dict
        A dictionary mapping test case name to xarray images.
      """
      results = {}
      for antialias, aa_descriptor in antialias_options:
          for canvas, canvas_descriptor in canvas_options:
              for func in (
                  generate_test_001,
                  generate_test_002,
                  generate_test_003,
                  generate_test_004,
                  generate_test_005,
                  generate_test_007,
              ):
                  points, name = func()
                  aggregators = draw_lines(canvas, points, antialias)
                  img = shade(aggregators, cmap=cmap01)
                  description = "{}_{}_{}".format(
                      name, aa_descriptor, canvas_descriptor
                  )
                  results[description] = img
  
              for func in (generate_test_006,):
                  points, name = func()
                  aggregator = draw_multi_segment_line(
                      canvas, points, antialias
                  )
                  img = shade(aggregator, cmap=cmap01)
                  description = "{}_{}_{}".format(
                      name, aa_descriptor, canvas_descriptor
                  )
                  results[description] = img
      return results
  
imports: import os
  import xarray
  import datashader
  import pandas
  import numpy
  import pytest
label_desc: Use image node_id 15 for calling a global function with example usage: generate_test_images() and returns: results