code: def test_bar(self):
      mpl.rcParams["date.converter"] = "concise"
  
      fig, (ax1, ax2) = plt.subplots(2, 1, layout="constrained")
  
      x_dates = np.array(
          [
              datetime.datetime(2020, 6, 30),
              datetime.datetime(2020, 7, 22),
              datetime.datetime(2020, 8, 3),
              datetime.datetime(2020, 9, 14),
          ],
          dtype=np.datetime64,
      )
      x_ranges = [8800, 2600, 8500, 7400]
  
      x = np.datetime64(datetime.datetime(2020, 6, 1))
      ax1.bar(x_dates, x_ranges, width=np.timedelta64(4, "D"))
      ax2.bar(np.arange(4), x_dates - x, bottom=x)
  
imports: import datetime
  import numpy
  import pytest
  import matplotlib.pyplot
  import matplotlib
label_desc: Use image node_id 8 for calling the TestDatetimePlotting obj's underlying member method code with example usage: obj.test_bar() without return types