Pytest with mock/pytest-mock

For some reason I cannot get mock.patch to work in any scenario when using Pytest. It simply doesn't do the patching. Am I using it incorrectly or is something messed up with my configuration?

base.py

def foo():
    return 'foo'

def get_foo():
    return foo()

test_base.py

import pytest
import mock
from pytest_mock import mocker

from base import get_foo

@mock.patch('base.foo') 
def test_get_foo(mock_foo):
    mock_foo.return_value = 'bar'
    assert get_foo() == 'bar'

def test_get_foo2(mocker):
    m = mocker.patch('base.foo', return_value='bar')
    assert get_foo() == 'bar'

def test_get_foo3():
    with mock.patch('base.foo', return_value='bar') as mock_foo:
        assert get_foo() == 'bar'

pytest results

============================================================= test session starts =============================================================
platform linux2 -- Python 2.7.13, pytest-3.0.7, py-1.4.33, pluggy-0.4.0
rootdir: /projects/git/ABC/query, inifile:
plugins: mock-1.6.0
collected 13 items 

test_base.py .....FFF.....

================================================================== FAILURES ===================================================================
________________________________________________________________ test_get_foo _________________________________________________________________

mock_foo = <MagicMock name='foo' id='140418877133648'>

    @mock.patch('base.foo')
    def test_get_foo(mock_foo):
        mock_foo.return_value = 'bar'
>       assert get_foo() == 'bar'
E       AssertionError: assert 'foo' == 'bar'
E         - foo
E         + bar

test_base.py:67: AssertionError
________________________________________________________________ test_get_foo2 ________________________________________________________________

mocker = <pytest_mock.MockFixture object at 0x7fb5d14bc210>

    def test_get_foo2(mocker):
        m = mocker.patch('base.foo', return_value='bar')
>       assert get_foo() == 'bar'
E       AssertionError: assert 'foo' == 'bar'
E         - foo
E         + bar

test_base.py:71: AssertionError
________________________________________________________________ test_get_foo3 ________________________________________________________________

    def test_get_foo3():
        with mock.patch('base.foo', return_value='bar') as mock_foo:
>           assert get_foo() == 'bar'
E           AssertionError: assert 'foo' == 'bar'
E             - foo
E             + bar

test_base.py:75: AssertionError