#./ehlo/ehlo.py

def say_ehlo():
    print 'EHLO'
    return False

#./hello/hello.py
from ehlo.ehlo import say_ehlo


def say_hello():
    print 'hello'
    return True


def say_hello_ehlo():
    say_hello()
    say_ehlo()
    return True

from hello.hello import say_hello_ehlo
from ehlo.ehlo import say_ehlo
from nose.tools import assert_true
from mock import patch


def test_say_hello_ehlo_mock():
    with patch('ehlo.ehlo.say_ehlo') as ehlo_mock:
        ehlo_mock.return_value = True
        assert_true(say_hello_ehlo())

$ PYTHONPATH=`pwd` nosetests -s test_hello.py
hello
EHLO
.
----------------------------------------------------------------------
Ran 1 test in 0.001s

OK

    with patch('ehlo.ehlo.say_ehlo') as ehlo_mock:
        from hello.hello import say_hello_ehlo
        ehlo_mock.return_value = True
        assert_true(say_hello_ehlo())

def test_say_hello_hello_mock():
    with patch('hello.hello.say_ehlo') as ehlo_mock:
        ehlo_mock.return_value = True
        assert_true(say_hello_ehlo())


def test_say_ehlo_ehlo_mock():
    with patch('ehlo.ehlo.say_ehlo') as ehlo_mock:
        ehlo_mock.return_value = True
        assert_true(say_hello_ehlo())

(17:42) novel@dev:~/tmp/mck1 %> ls
ehlo           hello          test_hello.py  test_hello.pyc
(17:42) novel@dev:~/tmp/mck1 %> PYTHONPATH=`pwd` nosetests -s test_hello.py
hello
<MagicMock name='say_ehlo' id='34445430864'>
.
----------------------------------------------------------------------
Ran 1 test in 0.002s

OK
(17:42) novel@dev:~/tmp/mck1 %> cat test_hello.py
from hello.hello import say_hello_ehlo
from ehlo.ehlo import say_ehlo
from nose.tools import assert_true
from mock import patch


def test_say_hello_ehlo_mock():
    with patch('hello.hello.say_ehlo') as ehlo_mock:
        ehlo_mock.return_value = True
        assert_true(say_hello_ehlo())
(17:42) novel@dev:~/tmp/mck1 %>

(17:54) novel@dev:~/tmp/mck1 %> cat ehlo/ehlo.py

def say_ehlo():
    print 'EHLO'
    return False

(17:54) novel@dev:~/tmp/mck1 %> cat hello/hello.py
from ehlo.ehlo import say_ehlo


def say_hello():
    print 'hello'
    return True


def say_hello_ehlo():
    say_hello()
    print say_ehlo
    say_ehlo()
    return True
(17:54) novel@dev:~/tmp/mck1 %> pip show mock
---
Name: mock
Version: 1.0.1
Location: /usr/local/lib/python2.7/site-packages
Requires:
(17:54) novel@dev:~/tmp/mck1 %>