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我正在尝试编写单元测试用例来通过模拟数据库来测试以下方法。如何在不实际连接到真实数据库服务器的情况下模拟数据库连接。我尝试了示例测试用例。我不确定这是否是正确的方法。如果我错了，请纠正我。

//MySQL.py
    class MySQL():

        retry_interval = 20000 

        def link(self, server,port):
            try:
                return pymysql.connect(server, username='name', passwd='pwd', db='demo', int(port))
                sys.stdout.write('Connected to database at {}:{}\n'.format(server,port))
            except:
                sys.stderr.write('Retry database connection in {} ms...\n'.format(self.retry_interval))
                sleep(self.retry_interval/1000.0)
                continue

//test.py
from unittest.mock import Mock, MagicMock
from unittest.mock import patch
import MySQL

   @patch('MySQL.pymysql')
    def testLink(self, mysql_mock):
        mock_cursor = Mock.MagicMock()
        mysql_mock.connect.return_value.cursor.return_value.__enter__.return_value = mock_cursor
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1 回答 1

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您可以真正测试的唯一有用的东西MySQL.pymysql是该connect方法，因此您不妨直接修补它：

//test.py
from unittest.mock import Mock, MagicMock
from unittest.mock import patch, call
import MySQL

@patch('MySQL.pymysql.connect')
def testLink(self, connect_mock):
    # You can configure a return value for the connection if you need to...
    connect_mock.return_value = MagicMock(name='connection_return', return_value=...)

    # You can now test that your connection is being called...
    self.assertEqual(1, connect_mock.call_count)

    # You can also check the call parameters...
    self.assertEqual(connect_mock.call_args_list[0], call(server, username='name', passwd='pwd',...))
于 2017-11-06T11:25:07.190 回答