code: def test_generate_color_map():
      colors = _generate_colormap(0)
      assert len(colors) == 0
  
      colors = _generate_colormap(1)
      assert len(colors) == 1
      assert len(colors[0]) == 4
  
      colors = _generate_colormap(-1)
      assert len(colors) == 0
  
      colors = _generate_colormap(5)
      assert len(colors) == 5
  
      # test unique
      num_colors = 385  # max number of unique colors avalible
      colors = _generate_colormap(num_colors)
      unique_rows = np.unique(colors, axis=0)
      assert unique_rows.shape[0] == num_colors
  
imports: import numpy
  import random
  import pytest
  from unittest import mock
  import matplotlib.pyplot
  from pathlib import Path
  from cleanlab.internal.multilabel_scorer import softmin
  from cleanlab.internal.segmentation_utils import _check_input, _get_valid_optional_params, _get_summary_optional_params
  from cleanlab.segmentation.filter import find_label_issues
  from cleanlab.segmentation.rank import get_label_quality_scores, issues_from_scores, _get_label_quality_per_image
  from cleanlab.segmentation.summary import display_issues, common_label_issues, filter_by_class, _generate_colormap
label_desc: Use image node_id 16 for calling a global function with example usage: test_generate_color_map() without return types