old_contents: from intervals import Interval
  
  
  class TestArithmeticOperators(object):
      def test_add_operator(self):
          assert Interval(1, 2) + Interval(1, 2) == Interval(2, 4)
  
      def test_sub_operator(self):
          assert Interval(1, 3) - Interval(1, 2) == Interval(-1, 2)
  
      def test_isub_operator(self):
          range_ = Interval(1, 3)
          range_ -= Interval(1, 2)
          assert range_ == Interval(-1, 2)
  
      def test_iadd_operator(self):
          range_ = Interval(1, 2)
          range_ += Interval(1, 2)
          assert range_ == Interval(2, 4)
  
new_contents: from pytest import mark
  from intervals import Interval
  
  
  class TestArithmeticOperators(object):
      def test_add_operator(self):
          assert Interval(1, 2) + Interval(1, 2) == Interval(2, 4)
  
      def test_sub_operator(self):
          assert Interval(1, 3) - Interval(1, 2) == Interval(-1, 2)
  
      def test_isub_operator(self):
          range_ = Interval(1, 3)
          range_ -= Interval(1, 2)
          assert range_ == Interval(-1, 2)
  
      def test_iadd_operator(self):
          range_ = Interval(1, 2)
          range_ += Interval(1, 2)
          assert range_ == Interval(2, 4)
  
      @mark.parametrize(('first', 'second', 'intersection'), (
          ('[1, 5]', '[2, 9]', '[2, 5]'),
          ('[3, 4]', '[3, 9]', '[3, 4]'),
          ('(3, 6]', '[2, 6)', '(3, 6)')
      ))
      def test_intersection(self, first, second, intersection):
          Interval(first) & Interval(second) == Interval(intersection)
  
subject: Add some tests for intersection