In a function I'm using uuid1 that I want to patch.
def myFunction():
my_value = uuid4.int
smth else..
I want to be able to mock my_value so it always returns the same number in my unit test, because I need it for further use. I tried doing:
@patch('folder.myFunction.uuid4')
def test_myFunction(self, mock_value):
mock_value.return_value = 22222
But it throws an error saying myFunction does not have uuid4 as an attribute.
How do I mock its value?
The error you get is correct. Your function does not have a uuid4 attribute.
I'm reading between the lines assuming uuid4 is a method of the uuid module that normally generates a random uuid.
When testing you said you want it to always return the same value. To do that you can substitute a unittest.mock.Mock for uuid.uuid4.
In [36]: uuid_mock = Mock(return_value=uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e'))
In [37]: uuid_mock()
Out[37]: UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e')
Something like this for testing the following function (f)
import uuid, unittest
from unittest.mock import Mock, patch
def f():
z = uuid.uuid4()
return z.int
The target for the patch is the uuid method - uuid.uuid4. Specify a unittest.mock.Mock with a fixed return value for the new parameter of the patch. During the test, the Mock will be substituted for uuid.uuid4
class TestF(unittest.TestCase):
uuid_mock = Mock(return_value=uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e'))
good_uuid = uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e').int
bad_uuid = uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b5a31').int
@patch(target='uuid.uuid4', new=TestF.uuid_mock)
def test_myFunction_True(self):
self.assertEqual(f(), self.good_uuid)
@patch(target='uuid.uuid4', new=TestF.uuid_mock)
def test_myFunction_False(self):
self.assertNotEqual(f(), self.bad_uuid)
if __name__ == '__main__':
unittest.main()
Result:
..
----------------------------------------------------------------------
Ran 2 tests in 0.001s
OK
If you want to test a function that relies on f's return value and you want f to always return the same value during testing then make f the target for the patch.
def g():
return f() == uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e').int
class TestG(unittest.TestCase):
good_uuid_mock = Mock(return_value=uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b9f3e').int)
bad_uuid_mock = Mock(return_value=uuid.UUID('77f1df52-4b43-11e9-910f-b8ca3a9b5a31').int)
@patch(target='__main__.f', new=TestG.good_uuid_mock)
def test_myFunction_True(self):
self.assertTrue(g())
@patch(target='__main__.f', new=TestG.bad_uuid_mock)
def test_myFunction_False(self):
self.assertFalse(g())
It depends on your import. Let's say you have a module called module.py, and you have an import like this:
from uuid import uuid4
This means that in this module we now have a variable called uuid4. This is the thing to mock.
@patch('path.to.module.uuid4.int')