old_contents: import chime.app
  
  def test_sample():
      assert chime.app.S == 4119405
  
  
new_contents: import pytest
  
  from penn_chime.models import sir
  from penn_chime.presentation import display_header
  
  
  # set up
  class MockStreamlit:
      def __init__(self):
          self.render_store = []
          self.markdown = self.just_store_instead_of_rendering
          self.latex = self.just_store_instead_of_rendering
          self.subheader = self.just_store_instead_of_rendering
  
      def just_store_instead_of_rendering(self, inp, *args, **kwargs):
          self.render_store.append(inp)
          return None
  
  
  st = MockStreamlit()
  
  
  def test_header():
      penn_css = '<link rel="stylesheet" href="https://www1.pennmedicine.org/styles/shared/penn-medicine-header.css">'
      display_header(st, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
      assert len(
          list(filter(lambda s: penn_css in s, st.render_store))
      ), "The Penn Medicine header should be printed"
  
  
  @pytest.mark.xfail()
  def test_header_fail():
      some_garbage = 'ajskhlaeHFPIQONOI8QH34TRNAOP8ESYAW4'
      display_header(st, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
      assert len(
          list(filter(lambda s: some_garbage in s, st.render_store))
      ), "This should fail"
  
  # Test the math
  
  
  def test_sir():
      """
      Someone who is good at testing, help
      """
      assert sir((100, 1, 0), 0.2, 0.5, 1) == (
          0.7920792079207921,
          0.20297029702970298,
          0.0049504950495049506,
      ), "This contrived example should work"
  
  
subject: add a few tests