code: def test_series_barh():
      ser = pd.Series([4, 5, 4, 5], index=["A", "B", "C", "D"])
      plot = ser.vgplot.barh()
      utils.validate_vegalite(plot)
      assert plot.mark == "bar"
      utils.check_encodings(plot, y="index", x="0")
  
imports: import pytest
  import pandas
  import altair
  from pdvega.tests import utils
label_desc: Use image node_id 16 for calling a global function with example usage: test_series_barh() without return types