python-unittest - 如何编写单元测试用例以在 Python 中检查与 SQL 服务器的数据库连接？

Question

我刚刚开始在 Python 中使用 unittest 来编写测试用例，我有一个与 SQL 服务器建立连接的函数。

sql_connection.py

def getConnection():
    connection = pyodbc.connect("Driver={ODBC Driver 13 for SQL Server};"
            "Server="+appConfig['sql_server']['server']+";"
            "Database="+appConfig['sql_server']['database']+";"
            "UID="+appConfig['sql_server']['uid']+";"
            "PWD="+appConfig['sql_server']['password']+";"
            "Trusted_Connection=no;",
            )
    return connection

我已经尝试过以下测试用例来检查数据库连接与否。

test_connection.py

import pyodbc

getConnection1=getConnection()

class TestDatabseConnection(unittest.TestCase):
    def test_getConnection(self):
        try:
            db_connection = getConnection1.connection
        except pyodbc.Error as ex:
            sqlstate = ex.args[1]
            print(sqlstate)
            self.fail(
                "getConnection() raised pyodbc.OperationalError. " +
                "Connection to database failed. Detailed error message: " + sqlstate)
        self.assertIsNone(db_connection)

但仍然无法获得成功。

======================================================================
ERROR: test_getConnection (__main__.TestDatabseConnection)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_connection.py", line 23, in test_getConnection
    db_connection = getConnection1.connection
AttributeError: 'pyodbc.Connection' object has no attribute 'connection'

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (errors=1)

请帮我解决这个问题。

标签： python-unittest

Answer 1

getConnection 的单元测试可能如下所示。我建议使用来自 unittest.mock 的补丁和模拟。通过单元测试，您只对测试 getConnection 的功能感兴趣，并且应该“模拟”函数中的所有其他函数调用。如果您想测试 pyodbc.connect 的全部潜力，那么我建议您进行实际连接到不再是单元测试的数据库的功能测试。有关补丁和 Mock 的更多信息，请查看文档。这些功能非常强大，使单元测试变得有趣和容易！单元测试.mock

import unittest
from unittest.mock import patch, Mock

import pyodbc

def getConnection():
    appConfig = {'sql_server': {'server':'', 'database':'', 'uid':'', 'password':''}}
    connection = pyodbc.connect("Driver={ODBC Driver 13 for SQL Server};"
            "Server="+appConfig['sql_server']['server']+";"
            "Database="+appConfig['sql_server']['database']+";"
            "UID="+appConfig['sql_server']['uid']+";"
            "PWD="+appConfig['sql_server']['password']+";"
            "Trusted_Connection=no;",
            )
    return connection


@patch('pyodbc_example.pyodbc')
class TestDatabseConnection(unittest.TestCase):
    def test_getConnection(self, pyodbc_mock):
        pyodbc_mock.connect.return_value = Mock()
        connection = getConnection()
        self.assertEqual(connection, pyodbc_mock.connect.return_value)