python - AssertionError: Exception not raised -

i have unittest test custom exception raised properly. got assertionerror: invalidlength not raised

below unit test

@patch('services.class_entity.validate') @patch('services.class_entity.jsonify') def test_should_raise_invalid_length_exception(self, mock_jsonify, mock_validate):     mock_validate.return_value = true      data = self.data     data['traditional_desc'] = "contrary popular"     mock_jsonify.return_value = {         "success": false,         "results": {             "message": "invalid value traditional_desc"         }     }      self.assertraises(invalidlength) cm:         benefittemplateservice.create(data) 

and function i'm testing

class benefittemplateservice(object):      @staticmethod     def create(params):          try:             required_fields = ['company_id', 'name', 'behavior', 'benefit_type']             valid = is_subset(params, required_fields)              if not valid:                 raise missingparameter              if not validate_string(params['traditional_desc'], 0, 1000, characters_supported="ascii"):                 raise invalidlength(400, "invalid value traditional_desc")              # call create here             response = benefittemplateentitymanager.create_template(params)             return response          except invalidlength e:             response = {                 "success": false,                 "results": {                     "message": e.message                 }             }              return jsonify(response), e.code 

the except invalidlength working because if try print execute line of code. assumed invalidlength exception being called i'm not sure on result of unittest fails. can please

create raises invalidlength exception catches , handles silently, test expects raise it.

use different assert assertraises. except block returns json, test can check json's content.