How to get direct return value instead of <MagicMock name='mock.xx' id='yy'> - unit-testing

Question

This is my testing code :
import mock
import unittest
def check_method_return(input):
return_value = input.ops.list()
if not return_value:
return False
return return_value
def check_method_len(input):
return_value = input.ops.list()
if len(return_value) < 1:
return False
return return_value
class TestMockReturnValue(unittest.TestCase):
def test_mock_return(self):
fake_input = mock.MagicMock()
fake_input().ops.list.return_value = []
result = check_method_return(fake_input)
self.assertFalse(result)
def test_mock_len(self):
fake_input = mock.MagicMock()
fake_input().ops.list.return_value = []
result = check_method_len(fake_input)
self.assertFalse(result)
if __name__ == '__main__':
test_empty = []
if not test_empty:
print("empty list equals to False")
unittest.main()
The run result output is :
empty list equals to False
.F
======================================================================
FAIL: test_mock_return (__main__.TestMockReturnValue)
----------------------------------------------------------------------
Traceback (most recent call last):
File "test_mock.py", line 31, in test_mock_return
self.assertFalse(result)
AssertionError: <MagicMock name='mock.ops.list()' id='140459969939728'> is not false
----------------------------------------------------------------------
Ran 2 tests in 0.005s
FAILED (failures=1)
Because when the list is empty, its return value for if is False. So, method "check_method_return" should work exactly the same as "check_method_len" in the real world.
So, my question is :
Is there a way to make the unit test pass for "check_method_return" ?

Answer 1

If this is the case, Here is the solution, I cannot explain the exact difference, but it makes sense:
# this mock away input.ops.list()
fake_input.ops.list.return_value = []
# this did not mock away input.ops.list()
fake_input().ops.list.return_value = []
To show the difference between 2 ways to set mock_input return value
This could help to understand better
[gliang#www ~]$ ipython
Python 2.6.6 (r266:84292, Jul 23 2015, 15:22:56)
IPython 0.13.2 -- An enhanced Interactive Python.
In [1]: import unittest
In [2]: import mock
In [3]: fake_input mock.Mag
mock.MagicMixin mock.MagicMock mock.MagicProxy
In [4]: fake_input = mock.MagicMock()
In [5]: fake_input().ops.list.return_value= []
In [6]: print fake_input().ops.list.return_value
[]
In [7]: print fake_input.ops.list.return_value
<MagicMock name='mock.ops.list()' id='15160848'>
In [8]: fake_input2 = mock.MagicMock()
In [9]: fake_input2.ops.list.return_value = []
In [10]: print fake_input2.ops.list.return_value
[]
In [11]: quit()