new_contents: # -*- coding: utf-8 -*-
  import numpy as np
  import ibei
  from astropy import units
  import unittest
  
  temp_sun = 5762.
  temp_earth = 288.
  bandgap = 1.15
  
  class Issues(unittest.TestCase):
      """
      Tests output types of the calculator methods.
      """
      def test_issue_1_devos_efficiency(self):
          """
          Unit system needs to be specified for astropy.constants.e to work.
          """
          try:
              ibei.devos_efficiency(bandgap, temp_sun, temp_earth, 1.09)
          except:
              self.fail("Unit system not initialized.")
  
subject: Add tests for issues causing exceptions