hacking/hacking/checks/mock_checks.py
Sean McGinnis b921c4de51 Add H216 to flag use of third party mock
Many projects use mocking in their unit tests, and most do not realize
that there is a difference between "import mock" and "import
unittest.mock", assuming that both use a standard part of the Python
library.

We've seen many cases where mock is not listed in the project's
requirements, but the code imports the third party mock instead of
unittest.mock. We've also seen a few break due to this, once their
dependencies have stopped pulling in that package for them.

There have also been several projects that have taken the effort to
switch all of there "import mock" statements over to "import
unittest.mock", as well as removing mock from their requirements, only
to then accidentally merge a patch that does "import mock" again because
it is hard to notice in code reviews.

This check is on by default. If a project is using the mock lib, then
they are able to explicitly do so by disabling this check. Otherwise,
projects don't need to take any action to get this protection, since
this is now the recommended default.

Change-Id: I8d255a00792a19279074703a8209a3699b480fd0
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>
2020-12-01 14:23:27 -06:00

177 lines
6.3 KiB
Python

# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import ast
import re
from hacking import core
@core.off_by_default
@core.flake8ext
class MockAutospecCheck(object):
"""Check for 'autospec' in mock.patch/mock.patch.object calls
Okay: mock.patch('target_module_1', autospec=True)
Okay: mock.patch('target_module_1', autospec=False)
Okay: mock.patch('target_module_1', autospec=None)
Okay: mock.patch('target_module_1', defined_mock)
Okay: mock.patch('target_module_1', new=defined_mock)
Okay: mock.patch('target_module_1', new_callable=SomeFunc)
Okay: mock.patch('target_module_1', defined_mock)
Okay: mock.patch('target_module_1', spec=1000)
Okay: mock.patch('target_module_1', spec_set=['data'])
Okay: mock.patch('target_module_1', wraps=some_obj)
H210: mock.patch('target_module_1')
Okay: mock.patch('target_module_1') # noqa
H210: mock.patch('target_module_1', somearg=23)
Okay: mock.patch('target_module_1', somearg=23) # noqa
Okay: mock.patch.object('target_module_2', 'attribute', autospec=True)
Okay: mock.patch.object('target_module_2', 'attribute', autospec=False)
Okay: mock.patch.object('target_module_2', 'attribute', autospec=None)
Okay: mock.patch.object('target_module_2', 'attribute', new=defined_mock)
Okay: mock.patch.object('target_module_2', 'attribute', defined_mock)
Okay: mock.patch.object('target_module_2', 'attribute', new_callable=AFunc)
Okay: mock.patch.object('target_module_2', 'attribute', spec=3)
Okay: mock.patch.object('target_module_2', 'attribute', spec_set=[3])
Okay: mock.patch.object('target_module_2', 'attribute', wraps=some_obj)
H210: mock.patch.object('target_module_2', 'attribute', somearg=2)
H210: mock.patch.object('target_module_2', 'attribute')
"""
name = "mock_check"
version = "1.00"
def __init__(self, tree, filename):
self.filename = filename
self.tree = tree
def run(self):
mcv = MockCheckVisitor(self.filename)
mcv.visit(self.tree)
for message in mcv.messages:
yield message
class MockCheckVisitor(ast.NodeVisitor):
# Patchers we are looking for and minimum number of 'args' without
# 'autospec' to not be flagged
patchers = {'mock.patch': 2, 'mock.patch.object': 3}
spec_keywords = {"autospec", "new", "new_callable", "spec", "spec_set",
"wraps"}
def __init__(self, filename):
super(MockCheckVisitor, self).__init__()
self.messages = []
self.filename = filename
def check_missing_autospec(self, call_node):
def find_autospec_keyword(keyword_node):
for keyword_obj in keyword_node:
keyword = keyword_obj.arg
# If they have defined autospec or new then it is okay
if keyword in self.spec_keywords:
return True
return False
if isinstance(call_node, ast.Call):
func_info = FunctionNameFinder(self.filename)
func_info.visit(call_node)
# We are only looking at our patchers
if func_info.function_name not in self.patchers:
return
min_args = self.patchers[func_info.function_name]
if not find_autospec_keyword(call_node.keywords):
if len(call_node.args) < min_args:
self.messages.append(
(call_node.lineno, call_node.col_offset,
"H210 Missing 'autospec' or 'spec_set' keyword in "
"mock.patch/mock.patch.object", MockCheckVisitor)
)
def visit_Call(self, node):
self.check_missing_autospec(node)
self.generic_visit(node)
class FunctionNameFinder(ast.NodeVisitor):
"""Finds the name of the function"""
def __init__(self, filename):
super(FunctionNameFinder, self).__init__()
self._func_name = []
self.filename = filename
@property
def function_name(self):
return '.'.join(reversed(self._func_name))
def visit_Name(self, node):
self._func_name.append(node.id)
self.generic_visit(node)
def visit_Attribute(self, node):
try:
self._func_name.append(node.attr)
self._func_name.append(node.value.id)
except AttributeError:
self.generic_visit(node)
def visit(self, node):
# If we get called with an ast.Call node, then work on the 'node.func',
# as we want the function name.
if isinstance(node, ast.Call):
return super(FunctionNameFinder, self).visit(node.func)
return super(FunctionNameFinder, self).visit(node)
third_party_mock = re.compile('^import.mock')
from_third_party_mock = re.compile('^from.mock.import')
@core.flake8ext
def hacking_no_third_party_mock(logical_line, noqa):
"""Check for use of mock instead of unittest.mock.
Projects have had issues with using mock without including it in their
requirements, thinking it is the standard library version. This makes it so
these projects need to explicitly turn off this check to make it clear they
intended to use it.
Okay: from unittest import mock
Okay: from unittest.mock import patch
Okay: import unittest.mock
H216: import mock
H216: from mock import patch
Okay: try: import mock
Okay: import mock # noqa
"""
msg = ('H216: The unittest.mock module should be used rather than the '
'third party mock package unless actually needed. If so, disable '
'the H216 check in hacking config and ensure mock is declared in '
"the project's requirements.")
if noqa:
return
if (re.match(third_party_mock, logical_line) or
re.match(from_third_party_mock, logical_line)):
yield (0, msg)