Пересмешивать переменную экземпляра в Python

Question

Я построил небольшую MySQL ORM в python, используя библиотеку mysql.connector, которую я использую для выполнения запросов.

Имя файла: mysql_db и хранится в utils

Mysql ORM:

import mysql.connector
from config import settings

class PythonMySqlOp:

    def __init__(self, host, user, passwd, database):
        self.host = host
        self.user = user
        self.passwd = passwd
        self.database = database

    def create_mysql_connector(self):
        mysql_connector = mysql.connector.connect(
            host=self.host,
            user=self.user,
            passwd=self.passwd,
            database=self.database
        )
        return mysql_connector

    def execute_query(self, query):
        try:
            mysql_connector = self.create_mysql_connector()
            cursor = mysql_connector.cursor(buffered=True)
            print('INFO: Executing: {}'.format(query))
            cursor.execute(query)

            query_results = []
            if not cursor:
                return query_results
            for query_result in cursor:
                query_results.append(query_result)
            cursor.close()
            # print('Query results: {}'.format(query_results))
            return query_results
        except Exception as e:
            raise Exception(e)

Это код, который требуетсяиспользовать это. Он называется batch_sql_cassandra_miner.py и хранится в batch

from utils import mysql_db
from constants import mysql_constants

class BatchSqlCassandraMiner:

    def __init__(self):
        self.mysql_db = mysql_db.PythonMysqlOp(
            mysql_constants.HOSTNAME,
            mysql_constants.USER,
            mysql_constants.PASSWORD,
            mysql_constants.DATABASE
        )

    def miner(self):
        '''a bunch of code here to build up the query'''

        query = ('sql query')
        try:
            results = self.mysql_db.execute_query(
                query
            )
            return results
        except Exception as e:
            raise Exception(e)

Мне нужно проверить этот метод miner. Вот что я придумал.

from batch import batch_sql_cassandra_miner
from unittest import TestCase
from unittest.mock import patch
from constants import mysql_constants

class TestBatchSqlCassandraMiner(unittest.TestCase):

    @patch('batch.batch_sql_cassandra_miner.BatchSqlCassandraMiner')
    @patch('utils.mysql_db.PythonMysqlOp')
    def setUp(self, mocked_mysql_op, mocked_batch_sql_cass_miner):
        self.batch_sql_cass_miner = batch_sql_cassandra_miner.BatchSqlCassandraMiner()

        ``` Mocks ```
        self.mocked_mysql_op = mocked_mysql_op
        self.mocked_batch_sql_cass_miner = mocked_batch_sql_cass_miner

    @patch('utils.mysql_db.PythonMysqlOp')
    def test_constructor(self, mocked_mysql_db):
        sql_cass_miner = batch_sql_cassandra_miner.BatchSqlCassandraMiner()
        mocked_mysql_db.assert_called_with(
            mysql_constants.HOSTNAME,
            mysql_constants.USER,
            mysql_constants.PASSWORD,
            mysql_constants.DATABASE
        )

    def test_miner_query_execution(self):
        pass


if __name__ == "__main__":
    unittest.main()

До этого момента тест проходит. Пересмотренная переменная MySQL называется.

(myvirtualenv) user@hostname:~/workspace$ python -m unittest discover -s 'tests/integration/batch_test/' -p 'test_*.py'
INFO  * Creating logs Directory: /logs
INFO * /logs: Directory already exists
..
----------------------------------------------------------------------
Ran 2 tests in 0.020s

OK

Итак, я проделал то же самое для test_miner_query_execution

from batch import batch_sql_cassandra_miner
from unittest import TestCase
from unittest.mock import patch
from constants import mysql_constants

class TestBatchSqlCassandraMiner(unittest.TestCase):

    @patch('batch.batch_sql_cassandra_miner.BatchSqlCassandraMiner')
    @patch('utils.mysql_db.PythonMysqlOp')
    def setUp(self, mocked_mysql_op, mocked_batch_sql_cass_miner):
        self.batch_sql_cass_miner = batch_sql_cassandra_miner.BatchSqlCassandraMiner()

        ``` Mocked Classes ```
        self.mocked_mysql_op = mocked_mysql_op
        self.mocked_batch_sql_cass_miner = mocked_batch_sql_cass_miner

    @patch('utils.mysql_db.PythonMysqlOp')
    def test_constructor(self, mocked_mysql_db):
        sql_cass_miner = batch_sql_cassandra_miner.BatchSqlCassandraMiner()
        mocked_mysql_db.assert_called_with(
            mysql_constants.HOSTNAME,
            mysql_constants.USER,
            mysql_constants.PASSWORD,
            mysql_constants.DATABASE
        )

    @patch('utils.mysql_db.PythonMysqlOp')
    def test_miner_query_execution(self, mocked_mysql_db):
        self.batch_sql_cass_miner.miner()
        mocked_mysql_db.execute_query.assert_called_with()


if __name__ == "__main__":
    unittest.main()

Сбой теста, при котором макет не вызывается

INFO  * Creating logs Directory: /home/spark/alt_balaji/logs
INFO * /home/spark/alt_balaji/logs: Directory already exists
..F
======================================================================
FAIL: test_get_exp_records (test_batch_sql_cassandra_miner.TestBatchSqlCassandraDump)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3.5/unittest/mock.py", line 1157, in patched
    return func(*args, **keywargs)
  File "/home/spark/alt_balaji/tests/integration/batch_test/test_batch_sql_cassandra_miner.py", line 54, in test_get_exp_records
    mocked_mysql_db.execute_query.assert_called_with()
  File "/usr/lib/python3.5/unittest/mock.py", line 783, in assert_called_with
    raise AssertionError('Expected call: %s\nNot called' % (expected,))
AssertionError: Expected call: execute_query()
Not called

----------------------------------------------------------------------
Ran 3 tests in 0.029s

FAILED (failures=1)

Итак, я подумал о создании фиктивного объекта. Затем я изменил метод test_miner_query_execution следующим образом:

def test_miner_query_execution(self):
    mocked_batch_sql_cass_miner_obj = self.mocked_batch_sql_cass_miner()

    # print(vars(mocked_batch_sql_cass_miner_obj))
    '''
    By printing this object I noticed that, this mock did not have the mysql_db instance variable under `_mock_children`, where everythingelse was located.
    So, I created the variable manually
    '''

    mocked_batch_sql_cass_miner_obj.mysql_db = self.mocked_mysql_db()


    # print(vars(mocked_batch_sql_cass_miner_obj))
    '''
    This time, `mysql_db` was registered as a `NonCallableMagicMock` and still not under `_mock_children`
    '''
    #print(vars(mocked_batch_sql_cass_miner_obj.mysql_db))
    '''
    The mysql_db variable did indeed have an execute_query method
    '''
    mocked_batch_sql_cass_miner_obj.miner()
    mocked_batch_sql_cass_miner_obj.mysql_db.execute_query.assert_called_with()

Нет результатов:

AssertionError: Expected call: execute_query()
Not called

----------------------------------------------------------------------
Ran 3 tests in 0.028s

Я просмотрел несколько ссылок на StackOverflow, но не нашел решения. Как мне посмеяться над поведением self.mysqldb, или мне вообще стоит над ним издеваться?