          """
          for input_value, expected_failure in get_items(self.invalid_inputs):
              with pytest.raises(serializers.ValidationError) as exc_info:
                  self.field.run_validation(input_value)
              assert exc_info.value.detail == expected_failure
  
      def test_outputs(self):
          for output_value, expected_output in get_items(self.outputs):
              assert self.field.to_representation(output_value) == expected_output
  
 
</s> remove             assert self.field.run_validation(input_value) == expected_output
 </s> add             assert self.field.run_validation(input_value) == expected_output, \
                'input value: {}'.format(repr(input_value)) </s> remove             assert self.field.to_representation(output_value) == expected_output
 </s> add             assert self.field.to_representation(output_value) == expected_output, \
                'output value: {}'.format(repr(output_value))
            assert exc_info.value.detail == expected_failure, \
                'input value: {}'.format(repr(input_value))
          """
          for input_value, expected_failure in get_items(self.invalid_inputs):
              with pytest.raises(serializers.ValidationError) as exc_info:
                  self.field.run_validation(input_value)
            assert exc_info.value.detail == expected_failure, \
                'input value: {}'.format(repr(input_value))
  
      def test_outputs(self):
          for output_value, expected_output in get_items(self.outputs):
              assert self.field.to_representation(output_value) == expected_output
  
keep keep keep keep replace keep keep keep keep keep
 Add repr(value) to the assert msg in FieldValues 
tests/test_fields.py