如何模拟pyun的stdin输入？

Question

我正在尝试测试一个接受输入的函数,stdin我目前正在测试这样的东西:

cat /usr/share/dict/words | ./spellchecker.py

在测试自动化的名义,有什么方法pyunit可以伪输入raw_input()？

Answer 1

简短的回答是猴子补丁 raw_input().

在如何在Python中显示重定向的stdin的答案中有一些很好的例子？

这是一个简单,琐碎的例子,它使用一个lambda抛出提示并返回我们想要的东西.

被测系统

cat ./name_getter.py
#!/usr/bin/env python

class NameGetter(object):

    def get_name(self):
        self.name = raw_input('What is your name? ')

    def greet(self):
        print 'Hello, ', self.name, '!'

    def run(self):
        self.get_name()
        self.greet()

if __name__ == '__main__':
    ng = NameGetter()
    ng.run()

$ echo Derek | ./name_getter.py 
What is your name? Hello,  Derek !

测试用例:

$ cat ./t_name_getter.py
#!/usr/bin/env python

import unittest
import name_getter

class TestNameGetter(unittest.TestCase):

    def test_get_alice(self):
        name_getter.raw_input = lambda _: 'Alice'
        ng = name_getter.NameGetter()
        ng.get_name()
        self.assertEquals(ng.name, 'Alice')

    def test_get_bob(self):
        name_getter.raw_input = lambda _: 'Bob'
        ng = name_getter.NameGetter()
        ng.get_name()
        self.assertEquals(ng.name, 'Bob')

if __name__ == '__main__':
    unittest.main()

$ ./t_name_getter.py -v
test_get_alice (__main__.TestNameGetter) ... ok
test_get_bob (__main__.TestNameGetter) ... ok

----------------------------------------------------------------------
Ran 2 tests in 0.000s

OK

Answer 2

更新 - 使用unittest.mock.patch

从python 3.3开始,有一个unittest名为mock的新子模块可以完全满足您的需要.对于使用Python 2.6或以上的有一个反向移植mock发现了这里.

import unittest
from unittest.mock import patch

import module_under_test


class MyTestCase(unittest.TestCase):

    def setUp(self):
        # raw_input is untouched before test
        assert module_under_test.raw_input is __builtins__.raw_input

    def test_using_with(self):
        input_data = "123"
        expected = int(input_data)

        with patch.object(module_under_test, "raw_input", create=True, 
                return_value=expected):
            # create=True is needed as raw_input is not in the globals of 
            # module_under_test, but actually found in __builtins__ .
            actual = module_under_test.function()

        self.assertEqual(expected, actual)

    @patch.object(module_under_test, "raw_input", create=True)
    def test_using_decorator(self, raw_input):
        raw_input.return_value = input_data = "123"
        expected = int(input_data)

        actual = module_under_test.function()

        self.assertEqual(expected, actual)

    def tearDown(self):
        # raw input is restored after test
        assert module_under_test.raw_input is __builtins__.raw_input

if __name__ == "__main__":
    unittest.main()
# where module_under_test.function is:
def function():
    return int(raw_input("prompt> "))

上一个答案 - 替换sys.stdin

我认为sys模块可能就是你想要的.

你可以做点什么

import sys

# save actual stdin in case we need it again later
stdin = sys.stdin

sys.stdin = open('simulatedInput.txt','r') 
# or whatever else you want to provide the input eg. StringIO

raw_input现在只要调用,就会从simulatedInput.txt中读取.如果是simulatedInput的内容是

hello
bob

然后第一次调用raw_input将返回"hello",第二次调用"bob",第三次调用EOFError,因为没有更多要读取的文本.