flake8-iw 0.0.17

A plugin to show lint errors for IW

flake8-iw

Linters for some common issues we encounter.- flake8-iw

• Building and testing
• Supported lint checks
  • IW01: Use of patch
  • IW02: Use of patch for time freeze
  • IW03: Error logging without exception info (exc_info)
  • IW04: Use of datetime.now
  • IW05: Use of datetime.replace(tzinfo=XXX)
  • IW06: Use of bulk_update/bulk_create without batch_size

Building and testing

Run command to build wheel and tarball.

python3 -m build
twine check --strict dist/*
twine upload dist/*

Run command to test.

pytest

Supported lint checks

IW01: Use of patch

Lint check to prevent the use of patch directly. Recommendation: Use PatchingTestCase / PatchingTransactionTestCase instead

Correct ✅

from instawork.tests import PatchingTestCase


class SignUpUpdatedTests(PatchingTestCase):
    def setUp(self):
        self.mock_call = self.patch("apps.auth.signals.task_send_email.delay")

    def test_email(self):
        expect(self.mock_call).to(have_been_called_once)

    def test_sms(self):
        mock_sms = self.patch("apps.auth.signals.task_send_sms.delay")
        expect(mock_sms).to(have_been_called_once)

Wrong ⚠️

from unittest.mock import patch


class SignUpUpdatedTests(TestCase):
    def setUp(self):
        self.patcher = patch("apps.auth.signals.task_send_email.delay")
        self.mock_email = self.patcher.start()

    def tearDown(self):
        self.patcher.stop()

    def test_email(self):
        ...
        expect(self.mock_email).to(have_been_called_once)

    @patch("apps.auth.signals.task_send_sms.delay")
    def test_sms(self, mock_sms):
        ...
        expect(mock_sms).to(have_been_called_once)

IW02: Use of patch for time freeze

Lint check to prevent the use of patch to freeze time. Recommendation: Use freeze_time from PatchingTestCase / PatchingTransactionTestCase or use freeze_time decorator or context manager from freezegun package.

Correct ✅

from django.utils import timezone
from instawork.tests import PatchingTestCase


class UserFeatureViewTests(PatchingTestCase):
    def setUp(self):
        self.now = timezone.now()

    def test_feature_view(self):
        ufv = None

        # Option 1
        with freeze_time(self.now):
            ufv = UserFeatureView.objects.get_or_create(
                user=self.shift.worker, feature=UserFeatureView.FEATURE_1
            )

        # Option 2
        self.freeze_time(self.now)
        ufv = UserFeatureView.objects.get_or_create(
            user=self.shift.worker, feature=UserFeatureView.FEATURE_1
        )

        ...

        expect(ufv.date_created).to(equal(self.now))

Wrong ⚠️

from django.utils import timezone
from instawork.tests import PatchingTestCase


class UserFeatureViewTests(PatchingTestCase):
    def setUp(self):
        self.now = timezone.now()
        self.mock_call = self.patch("django.utils.timezone.now", return_value=self.now)

    def test_feature_view(self):
        ufv = UserFeatureView.objects.get_or_create(
            user=self.shift.worker, feature=UserFeatureView.FEATURE_1
        )

        ...

        expect(ufv.date_created).to(equal(self.now))

IW03: Error logging without exception info (exc_info)

Lint check to prevent error logging without exception info. Recommendation: Add exc_info=True keyword argument in logger.error()

Correct ✅

import logging

custom_logger = logging.getLogger("module.logger")

class UserFeatureView(Model):
    def save(self):
        try:
            ...
        except ValueError as e:
            custom_logger.error(e, exc_info=True)
            return name

Wrong ⚠️

import logging

custom_logger = logging.getLogger("module.logger")

class UserFeatureView(Model):
    def save(self):
        try:
            ...
        except ValueError as e:
            custom_logger.error(e)
            return name

IW04: Use of datetime.now

Lint to avoid usage of datetime.now() which does not contain timezone information and causes various warnings in tests. Use timezone.now() instead.

Correct ✅

from django.utils import timezone

now = timezone.now()

Wrong ⚠️

from datetime import datetime

now = datetime.now()

IW05: Use of datetime.replace(tzinfo=XXX)

Lint to avoid usage of datetime.replace(tzinfo=XXX) which is not a viable way of setting timezones with python/pytz.

Correct ✅

import pytz
from django.utils import timezone

tz = pytz.timezone("America/Los_Angeles")
now_pt = timezone.now().astimezone(tz)

Wrong ⚠️

import pytz
from django.utils import timezone

tz = pytz.timezone("America/Los_Angeles")
now_pt = timezone.now().replace(tzinfo=tz)

IW06: Use of bulk_update/bulk_create without batch_size

Lint to avoid usage of Model.objects.bulk_update / Model.objects.bulk_create. Use Model.objects.bulk_update(batch_size=X) / Model.objects.bulk_create(batch_size=X) instead.

Correct ✅

# Bulk update
Model.objects.bulk_update([obj1, obj2, ...], batch_size=10)

# Bulk create
Model.objects.bulk_create([obj1, obj2, ...], batch_size=10)

Wrong ⚠️

# Bulk update
Model.objects.bulk_update([obj1, obj2, ...])

# Bulk create
Model.objects.bulk_create([obj1, obj2, ...])

IW07: IW07 use of celery.shared_task, use instawork.decorators.shared_task

Use our internal decorator instead: instawork.decorators.shared_task.

Correct ✅

from instawork.decorators import shared_task

@shared_task
def my_task():
    pass

Wrong ⚠️

from celery import shared_task

@shared_task
def my_task():
    pass

IW08 use of timezone.activate or timezone.deactivate, use with timezone.override instead

Lint to avoid usage of timezone.activate() and instead use with timezone.override(). This is to avoid timezone leakage between different tests and features.

Correct ✅

from django.utils import timezone
with timezone.override(zoneinfo.ZoneInfo(tzname)):
    <Rest of the code>

Wrong ⚠️

from django.utils import timezone
timezone.activate(zoneinfo.ZoneInfo(tzname))
<Rest of the code>
timezone.deactivate()