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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
751
In pytest , mocking can replace the return value of a function within a function. This is useful for testing the desired function and replacing the return value of a nested function within that desired function we are testing.
New in version 3.3. unittest.mock is a library for testing in Python. It allows you to replace parts of your system under test with mock objects and make assertions about how they have been used.
patch() unittest. mock provides a powerful mechanism for mocking objects, called patch() , which looks up an object in a given module and replaces that object with a Mock . Usually, you use patch() as a decorator or a context manager to provide a scope in which you will mock the target object.
MagicMock. MagicMock objects provide a simple mocking interface that allows you to set the return value or other behavior of the function or object creation call that you patched. This allows you to fully define the behavior of the call and avoid creating real objects, which can be onerous.
The problem was due to the relationship between my import specification and PATH variable. If I specified the entire path in the patch argument, like: @mock.patch('<PROJECT_ROOT>.<SUBPACKAGE>.base.foo') where PATH had the parent directory of as an entry, then it worked. I don't know why it wasn't throwing an import error if it wasn't finding base.foo. And if it wasn't finding it, I don't understand how the scope was different.
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