          delta_math = [e.name for e in
              Experiment.objects.filter(end__gte=F('start') + F('estimated_time') + datetime.timedelta(hours=1))]
          self.assertEqual(delta_math, ['e4'])
  
      @skipUnlessDBFeature("has_native_duration_field")
      def test_date_subtraction(self):
          under_estimate = [e.name for e in
              Experiment.objects.filter(estimated_time__gt=F('end') - F('start'))]
          self.assertEqual(under_estimate, ['e2'])
  
 
</s>
    @skipUnlessDBFeature('supports_temporal_subtraction')
          delta_math = [e.name for e in
              Experiment.objects.filter(end__gte=F('start') + F('estimated_time') + datetime.timedelta(hours=1))]
          self.assertEqual(delta_math, ['e4'])
  
    @skipUnlessDBFeature('supports_temporal_subtraction')
      def test_date_subtraction(self):
          under_estimate = [e.name for e in
              Experiment.objects.filter(estimated_time__gt=F('end') - F('start'))]
          self.assertEqual(under_estimate, ['e2'])
  
keep keep keep keep replace keep keep keep keep keep
 Fixed #24793 -- Unified temporal difference support.
tests/expressions/tests.py