fetchone()返回None，而不是在python中返回值

Question

我为我的项目编写了一个函数，该函数使用Pyodbc从MSSQL服务器获取数据。该功能运行良好。当我使用unittest和mock库编写unittest用例并模拟游标时。etchone并返回预定义的值，但在运行测试用例时，它返回None而不是返回值。这是我的密码。

Store.py

import os
from datetime import date
from datetime import timedelta
import logging
logging.basicConfig(filename="source_monitor.log", format='%(name)s - %(levelname)s - %(asctime)s %(message)s', filemode='a') 
logger=logging.getLogger() 

class KMExtracter:
def __init__(self,metric_collected_date):
self.metric_collected_date = metric_collected_date
# argument conn is a db connection which will passed in seperate program
def get_metrics_by_technology(self, conn, technology):
try:

cursor = conn.cursor()
cursor.execute(
"SELECT COUNT(*) FROM URL_STORE WHERE Technology='{0}' firstExtractionDate  BETWEEN '{1} 00:00:00' AND '{1} 23:59:59'".format(self.technology[technology],
self.metric_collected_date
))


count = cursor.fetchone()
return count[0]
except Exception as e:
logging.error("{0} at get_metrics_by_technology()".format(e))

testrongtore.py

class TestKM(unittest.TestCase):
def test_get_metrics_by_technology(self):
mock_data_interface = Mock()
mock_data_interface.cursor.return_value.execute.return_value.fetchone.return_value(23987,)

km = KMExtracter('2021-04-03')
print(km.get_metrics_by_technology(mock_data_interface, 'SOME'))
self.assertEqual(23987,km.get_metrics_by_technology(mock_data_interface, 'SOME'))

我得到的错误：断言错误：23987！=无

Answer 1

class TestKM(unittest.TestCase):
def test_get_metrics_by_technology(self):
mock_data_interface = Mock()

# execute.return_value was removed from the below line.
mock_data_interface.cursor.return_value.fetchone.return_value(23987,)

km = KMExtracter('2021-04-03')
print(km.get_metrics_by_technology(mock_data_interface, 'SOME'))
self.assertEqual(23987,km.get_metrics_by_technology(mock_data_interface, 'SOME'))