Django Nose Lint Quickstart - Enforce fast unit tests

In the battle for blazing fast unit tests, you need all the tools you can get at your disposal. Enter django-nose-lint, a new Nose plugin that lets you enforce certain runtime constraints on your test suite. You can just flat out fail tests that take over a configurable amount of time. You can also get more granular and fail tests that try to do certain slow stuff. For example, using the Django test client.

Here are the things it can currently check for:

  • ESOK = Used a TCP socket
  • ECLI = Used the Django Test Client
  • ETEM = Tried to render a Django template
  • ESLO = Test took over 1 second (takes --maxms argument)
  • EALL = All of the above

Quickstart for exsting Django projects already using django-nose

If you're already running django-nose on your Django app, all you need to do is install django-nose-lint, and run your tests with the --lint flag.

pip install django-nose-lint
./manage.py test --lint=EALL

Starting from scratch on a new Django project

This is mostly an re-hash of the django-nose setup docs. I assume you have virtualenv installed, and want to use it to isolate this skunkworks from your existing python stuff.

First, setup a new Django project inside virtualenv.

mkdir django-nose-lint-test
cd django-nose-lint-test/
virtualenv --no-site-packages --distribute virtualenv
source virtualenv/bin/activate
pip install django nose django-nose django-nose-lint
django-admin.py startproject mysite
cd mysite/

Then, edit your Django settings.py file to do basic setup, and attach django-nose.

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': '',
    }
}

INSTALLED_APPS = (
    ...
    'django_nose',
)

TEST_RUNNER = 'django_nose.NoseTestSuiteRunner'

Create a basic test that we want to fail. Create this as mysite/tests.py. It should be along-side urls.py in the directory structure.

import unittest
import time


class MyTest(unittest.TestCase):

    def test_one(self):
        time.sleep(1.1)
        self.assertTrue(True)

Run your test suite.

>python manage.py test --lint=EALL
Creating test database for alias 'default'...
.E
======================================================================
ERROR: test_one (tests.MyTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/nose/case.py", line 133, in run
    self.runTest(result)
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/nose/case.py", line 151, in runTest
    test(result)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/case.py", line 376, in __call__
    return self.run(*args, **kwds)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/case.py", line 355, in run
    result.stopTest(self)
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/nose/proxy.py", line 180, in stopTest
    self.plugins.stopTest(self.test)
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/nose/plugins/manager.py", line 99, in __call__
    return self.call(*arg, **kw)
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/nose/plugins/manager.py", line 167, in simple
    result = meth(*arg, **kw)
  File "/Users/cseibert/projects/django-nose-lint-test/virtualenv/lib/python2.7/site-packages/noselint/__init__.py", line 76, in stopTest
    raise DeprecationWarning('DjangoNoseLint Error: ESLO - test took %s ms' % delta_ms)
DeprecationWarning: DjangoNoseLint Error: ESLO - test took 1101 ms

----------------------------------------------------------------------
Ran 1 test in 1.104s

FAILED (errors=1)

If you run without the --lint flag, the same test should pass.

Call for ideas

I'm looking for some more ideas of things to fail in unit tests. Please submit a bug to the tracker if you have any ideas.



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