new_contents: import pytest
  
  import pandas as pd
  
  from ceam.modules.opportunistic_screening import _hypertensive_categories, OpportunisticScreeningModule
  
  def _population_factory():
      population = []
      population.append((40, 130)) # Normotensive, below 60
      population.append((60, 145)) # Normotensive, exactly 60
      population.append((70, 145)) # Normotensive, above 60
  
      population.append((40, 140)) # Hypertensive, below 60
      population.append((40, 145)) # Hypertensive, below 60
      population.append((60, 170)) # Hypertensive, exatly 60
      population.append((70, 150)) # Hypertensive, above 60
      population.append((70, 155)) # Hypertensive, above 60
  
      population.append((40, 185)) # Severe hypertensive, below 60
      population.append((70, 185)) # Severe hypertensive, above 60
  
      return pd.DataFrame(population, columns=['age', 'systolic_blood_pressure'])
  
  
  def test_hypertensive_categories():
      population = _population_factory()
  
      normotensive, hypertensive, severe_hypertension = _hypertensive_categories(population)
  
      assert len(normotensive) == 3
      assert len(hypertensive) == 5
      assert len(severe_hypertension) == 2
  
subject: Test for _hypertensive_categories