Python 如何模拟在同一文件中定义的函数，而不是由被测试的方法导入的函数？

到目前为止，我有以下代码：

import unittest
from mock import patch, Mock


def method_1():
    from math import ceil
    return ceil(1.2)


def test_1():
    m = Mock(return_value=10)
    with patch('math.ceil', m) as p:
        a = method_1()
        assert(a == 10)


def method_2():
    return method_1() + 1


def test_2():
    m = Mock(return_value=20)
    with patch('method_1', m) as p:
        a = method_2()
        assert(a == 21)

在运行测试时，我得到以下错误：

$ nosetests -s unittest.py 
.E
======================================================================
ERROR: unittest.test_2
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/srv/www/rpr/unittest.py", line 27, in test_2
    with patch('method_1', m) as p:
  File "/usr/local/lib/python2.7/dist-packages/mock.py", line 1564, in patch
    getter, attribute = _get_target(target)
  File "/usr/local/lib/python2.7/dist-packages/mock.py", line 1413, in _get_target
    (target,))
TypeError: Need a valid target to patch. You supplied: 'method_1'

----------------------------------------------------------------------
Ran 2 tests in 27.840s

FAILED (errors=1)

---

我能够正确模拟

math.ceil

，并且

test_1

顺利通过。我很难模仿

方法1

本身。我如何做到这一点？

我必须将

test_2

更改为以下内容才能使其正常工作：

def test_2():
    m = Mock(return_value=20)
    with patch(__name__ + '.method_1', m) as p:
        a = method_2()
        assert(a == 21)