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[英]How to run pytest with a specified test directory on a file that uses argparse?
[英]Pytest with argparse: how to test user is prompted for confirmation?
我有一个CLI工具,并希望测试是否提示用户使用input()
确认选择。 这与在Python 2中使用raw_input()
。
要测试的(释义)代码如下:
import sys
import argparse
def confirm():
notification_str = "Please respond with 'y' or 'n'"
while True:
choice = input("Confirm [Y/n]?").lower()
if choice in 'yes' or not choice:
return True
if choice in 'no':
return False
print(notification_str)
def parse_args(args):
parser = argparse.ArgumentParser()
parser.add_argument('-d', '--destructive', action='store_true')
return parser.parse_args()
def main():
args = parse_args(sys.argv[1:])
if args.destructive:
if not confirm():
sys.exit()
do_stuff(args)
if __name__ == '__main__':
main()
我使用pytest作为我的框架。 如何制作它以便我可以测试CLI中是否显示确认提示? 如果我尝试比较stdout
我得到错误: OSError: reading from stdin while output is captured
。
我想确保:
我将在另一个文件中使用以下代码:
import pytest
from module_name import main
def test_user_is_prompted_when_destructive_flag_is_set():
sys.argv['', '-d']
main()
assert _ # What the hell goes here?
def test_user_is_not_prompted_when_destructive_flag_not_set():
sys.argv['',]
main()
assert _ # And here too?
我建议使用confirm()
函数开始测试是一种更好的单元测试策略。 这允许在本地sys.stdio
input
和sys.stdio
类的东西。 然后,一旦确认确认按预期工作,就可以编写测试以验证是否以特定方式调用。 您可以为此编写测试,并在这些测试期间模拟confirm()
。
这是confirm()
的单元测试,它使用pytest.parametrize
和mock
来处理用户输入和输出:
@pytest.mark.parametrize("from_user, response, output", [
(['x', 'x', 'No'], False, "Please respond with 'y' or 'n'\n" * 2),
('y', True, ''),
('n', False, ''),
(['x', 'y'], True, "Please respond with 'y' or 'n'\n"),
])
def test_get_from_user(from_user, response, output):
from_user = list(from_user) if isinstance(from_user, list) else [from_user]
with mock.patch.object(builtins, 'input', lambda x: from_user.pop(0)):
with mock.patch('sys.stdout', new_callable=StringIO):
assert response == confirm()
assert output == sys.stdout.getvalue()
pytest.mark.parametrize
允许在条件下多次调用测试函数。 以下是4个简单的步骤,它们将测试confirm
大部分功能:
@pytest.mark.parametrize("from_user, response, output", [
(['x', 'x', 'No'], False, "Please respond with 'y' or 'n'\n" * 2),
('y', True, ''),
('n', False, ''),
(['x', 'y'], True, "Please respond with 'y' or 'n'\n"),
])
mock.patch
可用于临时替换模块中的函数(以及其他用途)。 在这种情况下,它用于替换input
和sys.stdout
以允许注入用户输入和捕获打印的字符串
with mock.patch.object(builtins, 'input', lambda x: from_user.pop(0)):
with mock.patch('sys.stdout', new_callable=StringIO):
最后运行测试中的函数并验证函数的输出和打印的任何字符串:
assert response == confirm()
assert output == sys.stdout.getvalue()
import sys
from io import StringIO
import pytest
from unittest import mock
import builtins
def confirm():
notification_str = "Please respond with 'y' or 'n'"
while True:
choice = input("Confirm [Y/n]?").lower()
if choice in 'yes' or not choice:
return True
if choice in 'no':
return False
print(notification_str)
@pytest.mark.parametrize("from_user, response, output", [
(['x', 'x', 'No'], False, "Please respond with 'y' or 'n'\n" * 2),
('y', True, ''),
('n', False, ''),
(['x', 'y'], True, "Please respond with 'y' or 'n'\n"),
])
def test_get_from_user(from_user, response, output):
from_user = list(from_user) if isinstance(from_user, list) \
else [from_user]
with mock.patch.object(builtins, 'input', lambda x: from_user.pop(0)):
with mock.patch('sys.stdout', new_callable=StringIO):
assert response == confirm()
assert output == sys.stdout.getvalue()
pytest.main('-x test.py'.split())
============================= test session starts =============================
platform win32 -- Python 3.6.3, pytest-3.3.2, py-1.5.2, pluggy-0.6.0
rootdir: C:\Users\stephen\Documents\src\testcode, inifile:
collected 4 items
test.py .... [100%]
========================== 4 passed in 0.15 seconds ===========================
confirm()
: 要测试在预期时调用confirm,并且程序在调用时按预期响应,可以使用unittest.mock
来模拟confirm()
。
注意:在通常的unittest方案中, confirm
将在不同的文件中,并且mock.patch
可以以类似的方式用于在此示例中修补sys.argv
方式。
confirm()
: import sys
import argparse
def confirm():
pass
def parse_args(args):
parser = argparse.ArgumentParser()
parser.add_argument('-d', '--destructive', action='store_true')
return parser.parse_args()
def main():
args = parse_args(sys.argv[1:])
if args.destructive:
if not confirm():
sys.exit()
import pytest
from unittest import mock
@pytest.mark.parametrize("argv, called, response", [
([], False, None),
(['-d'], True, False),
(['-d'], True, True),
])
def test_get_from_user(argv, called, response):
global confirm
original_confirm = confirm
confirm = mock.Mock(return_value=response)
with mock.patch('sys.argv', [''] + argv):
if called and not response:
with pytest.raises(SystemExit):
main()
else:
main()
assert confirm.called == called
confirm = original_confirm
pytest.main('-x test.py'.split())
============================= test session starts =============================
platform win32 -- Python 3.6.3, pytest-3.3.2, py-1.5.2, pluggy-0.6.0
rootdir: C:\Users\stephen\Documents\src\testcode, inifile:
collected 3 items
test.py ... [100%]
========================== 3 passed in 3.26 seconds ===========================
enter code here
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