code: def test_data2html_img():
      assert (
          nbcollection.data2html_img(bytes([0]))
          == '<img src="data:image/png;base64, AA==\n"/>'
      )
  
imports: import pytest
  import pandas
  import numpy
  from sklearn_evaluation import NotebookCollection
  from sklearn_evaluation.nb import NotebookCollection
  from IPython.display import HTML
label_desc: Use image node_id 7 for calling a global function with example usage: test_data2html_img() without return types