class_docstr: Test resolve_colors helper function
class_docstr_tok: ["Test","resolve_colors","helper","function"]
docstr: Check colormap when n_colors is not specified
docstr_tok: ["Check","colormap","when","n_colors","is","not","specified"]
code: def test_colormap_string_default_length(self):
      """
      Check colormap when n_colors is not specified
      """
      n_colors = len(get_color_cycle())
      assert len(resolve_colors(colormap="autumn")) == n_colors
  
imports: import sys
  import pytest
  from matplotlib import cm
  from cycler import Cycler
  from sklearn.cluster import KMeans
  from sklearn.datasets import make_blobs
  from yellowbrick.style.colors import *
  from yellowbrick.style.palettes import ColorPalette, PALETTES
  from yellowbrick.cluster.silhouette import SilhouetteVisualizer
  from tests.base import VisualTestCase
label_desc: Use image node_id 7 for calling the TestResolveColors obj's underlying member method code with example usage: obj.test_colormap_string_default_length() without return types