Python 模拟 Patch os.environ 和返回值

使用 mock 进行单元测试 con () :

App py

import mysql.connector
import os, urlparse




def conn():
if "DATABASE_URL" in os.environ:
url = urlparse(os.environ["DATABASE_URL"])
g.db = mysql.connector.connect(
user=url.username,
password=url.password,
host=url.hostname,
database=url.path[1:],
)
else:
return "Error"

Test.py

def test_conn(self):
with patch(app.mysql.connector) as mock_mysql:
with patch(app.os.environ) as mock_environ:
con()
mock_mysql.connect.assert_callled_with("credentials")

错误: 未调用 断言mock_mysql.connect.assert_called_with。

我相信这是因为“ Database _ url”不在我的补丁 os.environ中，而且因为这个测试调用没有发送到 mysql _ mock。连接。

问题:

  1. 要使这个测试代码工作，我需要做哪些更改？

  2. 我也要修补 urlparse吗？

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最佳答案

You can try unittest.mock.patch.dict solution. Just call conn with a dummy argument:

import mysql.connector
import os, urlparse
from unittest import mock




@mock.patch.dict(os.environ, {"DATABASE_URL": "mytemp"}, clear=True)  # why need clear=True explained here https://stackoverflow.com/a/67477901/248616
def conn(mock_A):
print os.environ["mytemp"]
if "DATABASE_URL" in os.environ:
url = urlparse(os.environ["DATABASE_URL"])
g.db = mysql.connector.connect(
user=url.username,
password=url.password,
host=url.hostname,
database=url.path[1:],
)
else:
return "Error"

Or if you don't want to modify your original function try this solution:

import os
from unittest import mock


def func():
print os.environ["mytemp"]




def test_func():
k = mock.patch.dict(os.environ, {"mytemp": "mytemp"})
k.start()
func()
k.stop()




test_func()
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You can also use something like the modified_environ context manager describe in this question to set/restore the environment variables.

with modified_environ(DATABASE_URL='mytemp'):
func()
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For this, I find that pytest's monkeypatch fixture leads to better code when you need to set environment variables:

def test_conn(monkeypatch):
monkeypatch.setenv('DATABASE_URL', '<URL WITH CREDENTIAL PARAMETERS>')
with patch(app.mysql.connector) as mock_mysql:
conn()
mock_mysql.connect.assert_called_with(<CREDENTIAL PARAMETERS>)
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The accepted answer is correct. Here's a decorator @mockenv to do the same.

def mockenv(**envvars):
return mock.patch.dict(os.environ, envvars)




@mockenv(DATABASE_URL="foo", EMAIL="bar@gmail.com")
def test_something():
assert os.getenv("DATABASE_URL") == "foo"
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At the head of your file mock environ before importing your module:

with patch.dict(os.environ, {'key': 'mock-value'}):
import your.module
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In my use case, I was trying to mock having NO environmental variable set. To do that, make sure you add clear=True to your patch.

with patch.dict(os.environ, {}, clear=True):
func()
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Little improvement to answer here

@mock.patch.dict(os.environ, {"DATABASE_URL": "foo", "EMAIL": "bar@gmail.com"})
def test_something():
assert os.getenv("DATABASE_URL") == "foo"

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