text: import unittest
  
  from binary_search import binary_search
  
  
  class BinarySearchTests(unittest.TestCase):
      def test_finds_value_in_array_with_one_element(self):
          self.assertEqual(binary_search([6], 6), 0)
  
      def test_finds_value_in_middle_of_array(self):
          self.assertEqual(binary_search([1, 3, 4, 6, 8, 9, 11], 6), 3)
  
      def test_finds_value_at_beginning_of_array(self):
          self.assertEqual(binary_search([1, 3, 4, 6, 8, 9, 11], 1), 0)
  
      def test_finds_value_at_end_of_array(self):
          self.assertEqual(binary_search([1, 3, 4, 6, 8, 9, 11], 11), 6)
  
      def test_finds_value_in_array_of_odd_length(self):
          self.assertEqual(
              binary_search([1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 634],
                            144), 9)
  
      def test_finds_value_in_array_of_even_length(self):
          self.assertEqual(
              binary_search([1, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377], 21),
              5)
  
      def test_identifies_value_missing(self):
          self.assertRaises(ValueError, binary_search, [1, 3, 4, 6, 8, 9, 11], 7)
  
      def test_value_smaller_than_arrays_minimum(self):
          self.assertRaises(ValueError, binary_search, [1, 3, 4, 6, 8, 9, 11], 0)
  
      def test_value_larger_than_arrays_maximum(self):
          self.assertRaises(ValueError, binary_search, [1, 3, 4, 6, 8, 9, 11],
                            13)
  
      def test_empty_array(self):
          self.assertRaises(ValueError, binary_search, [], 1)
  
  
  if __name__ == '__main__':
      unittest.main()
  