test_waffle.py

from __future__ import unicode_literals

import random
import threading
import unittest

from django.conf import settings
from django.contrib.auth.models import AnonymousUser, Group, User
from django.db import connection, transaction
from django.test import RequestFactory, TransactionTestCase
from django.test.utils import override_settings

import mock

import waffle
from test_app import views
from waffle.middleware import WaffleMiddleware
from waffle.models import Flag, Sample, Switch
from waffle.tests.base import TestCase


def get(**kw):
    request = RequestFactory().get('/foo', data=kw)
    request.user = AnonymousUser()
    return request


def process_request(request, view):
    response = view(request)
    return WaffleMiddleware().process_response(request, response)


class WaffleTests(TestCase):
    def test_persist_active_flag(self):
        Flag.objects.create(name='myflag', percent='0.1')
        request = get()

        # Flag stays on.
        request.COOKIES['dwf_myflag'] = 'True'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' in response.cookies
        self.assertEqual('True', response.cookies['dwf_myflag'].value)

    def test_persist_inactive_flag(self):
        Flag.objects.create(name='myflag', percent='99.9')
        request = get()

        # Flag stays off.
        request.COOKIES['dwf_myflag'] = 'False'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' in response.cookies
        self.assertEqual('False', response.cookies['dwf_myflag'].value)

    def test_no_set_unused_flag(self):
        """An unused flag shouldn't have its cookie reset."""
        request = get()
        request.COOKIES['dwf_unused'] = 'True'
        response = process_request(request, views.flag_in_view)
        assert 'dwf_unused' not in response.cookies

    def test_superuser(self):
        """Test the superuser switch."""
        Flag.objects.create(name='myflag', superusers=True)
        request = get()
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

        superuser = User(username='foo', is_superuser=True)
        request.user = superuser
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

        non_superuser = User(username='bar', is_superuser=False)
        non_superuser.save()
        request.user = non_superuser
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_staff(self):
        """Test the staff switch."""
        Flag.objects.create(name='myflag', staff=True)
        request = get()
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

        staff = User(username='foo', is_staff=True)
        request.user = staff
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

        non_staff = User(username='foo', is_staff=False)
        non_staff.save()
        request.user = non_staff
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_languages(self):
        Flag.objects.create(name='myflag', languages='en,fr')
        request = get()
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)

        request.LANGUAGE_CODE = 'en'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)

        request.LANGUAGE_CODE = 'de'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)

    def test_user(self):
        """Test the per-user switch."""
        user = User.objects.create(username='foo')
        flag = Flag.objects.create(name='myflag')
        flag.users.add(user)

        request = get()
        request.user = user
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

        request.user = User.objects.create(username='someone_else')
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_group(self):
        """Test the per-group switch."""
        group = Group.objects.create(name='foo')
        user = User.objects.create(username='bar')
        user.groups.add(group)

        flag = Flag.objects.create(name='myflag')
        flag.groups.add(group)

        request = get()
        request.user = user
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

        request.user = User(username='someone_else')
        request.user.save()
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_authenticated(self):
        """Test the authenticated/anonymous switch."""
        Flag.objects.create(name='myflag', authenticated=True)

        request = get()
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

        request.user = User(username='foo')
        assert request.user.is_authenticated
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_everyone_on(self):
        """Test the 'everyone' switch on."""
        Flag.objects.create(name='myflag', everyone=True)

        request = get()
        request.COOKIES['dwf_myflag'] = 'False'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

        request.user = User(username='foo')
        assert request.user.is_authenticated
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'on', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_everyone_off(self):
        """Test the 'everyone' switch off."""
        Flag.objects.create(name='myflag', everyone=False,
                            authenticated=True)

        request = get()
        request.COOKIES['dwf_myflag'] = 'True'
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

        request.user = User(username='foo')
        assert request.user.is_authenticated
        response = process_request(request, views.flag_in_view)
        self.assertEqual(b'off', response.content)
        assert 'dwf_myflag' not in response.cookies

    def test_percent(self):
        """If you have no cookie, you get a cookie!"""
        Flag.objects.create(name='myflag', percent='50.0')
        request = get()
        response = process_request(request, views.flag_in_view)
        assert 'dwf_myflag' in response.cookies

    @mock.patch.object(random, 'uniform')
    def test_reroll(self, uniform):
        """Even without a cookie, calling flag_is_active twice should return
        the same value."""
        Flag.objects.create(name='myflag', percent='50.0')
        # Make sure we're not really random.
        request = get()  # Create a clean request.
        assert not hasattr(request, 'waffles')
        uniform.return_value = '10'  # < 50. Flag is True.
        assert waffle.flag_is_active(request, 'myflag')
        assert hasattr(request, 'waffles')  # We should record this flag.
        assert 'myflag' in request.waffles
        assert request.waffles['myflag'][0]
        uniform.return_value = '70'  # > 50. Normally, Flag would be False.
        assert waffle.flag_is_active(request, 'myflag')
        assert request.waffles['myflag'][0]

    def test_undefined(self):
        """Undefined flags are always false."""
        request = get()
        assert not waffle.flag_is_active(request, 'foo')

    @override_settings(WAFFLE_FLAG_DEFAULT=True)
    def test_undefined_default(self):
        """WAFFLE_FLAG_DEFAULT controls undefined flags."""
        request = get()
        assert waffle.flag_is_active(request, 'foo')

    @override_settings(WAFFLE_OVERRIDE=True)
    def test_override(self):
        request = get(foo='1')
        Flag.objects.create(name='foo')  # Off for everyone.
        assert waffle.flag_is_active(request, 'foo')

    def test_testing_flag(self):
        Flag.objects.create(name='foo', testing=True)
        request = get(dwft_foo='1')
        assert waffle.flag_is_active(request, 'foo')
        assert 'foo' in request.waffle_tests
        assert request.waffle_tests['foo']

        # GET param should override cookie
        request = get(dwft_foo='0')
        request.COOKIES['dwft_foo'] = 'True'
        assert not waffle.flag_is_active(request, 'foo')
        assert 'foo' in request.waffle_tests
        assert not request.waffle_tests['foo']

    def test_testing_disabled_flag(self):
        Flag.objects.create(name='foo')
        request = get(dwft_foo='1')
        assert not waffle.flag_is_active(request, 'foo')
        assert not hasattr(request, 'waffle_tests')

        request = get(dwft_foo='0')
        assert not waffle.flag_is_active(request, 'foo')
        assert not hasattr(request, 'waffle_tests')

    def test_set_then_unset_testing_flag(self):
        Flag.objects.create(name='myflag', testing=True)
        response = self.client.get('/flag_in_view?dwft_myflag=1')
        self.assertEqual(b'on', response.content)

        response = self.client.get('/flag_in_view')
        self.assertEqual(b'on', response.content)

        response = self.client.get('/flag_in_view?dwft_myflag=0')
        self.assertEqual(b'off', response.content)

        response = self.client.get('/flag_in_view')
        self.assertEqual(b'off', response.content)

        response = self.client.get('/flag_in_view?dwft_myflag=1')
        self.assertEqual(b'on', response.content)

    @override_settings(DATABASE_ROUTERS=['waffle.tests.base.ReplicationRouter'])
    def test_everyone_on_read_from_write_db(self):
        flag = Flag.objects.create(name='myflag', everyone=True)

        request = get()
        response = process_request(request, views.flag_in_view)
        # By default, flag_is_active should hit whatever it configured as the
        # read DB (so values will be stale if replication is lagged).
        self.assertEqual(b'off', response.content)

        with override_settings(WAFFLE_READ_FROM_WRITE_DB=True):
            # Save the flag again to flush the cache.
            flag.save()

            # The next read should now be directed to the write DB, ensuring
            # the cache and DB are in sync.
            response = process_request(request, views.flag_in_view)
            self.assertEqual(b'on', response.content)


class SwitchTests(TestCase):
    def test_switch_active(self):
        switch = Switch.objects.create(name='myswitch', active=True)
        assert waffle.switch_is_active(switch.name)

    def test_switch_inactive(self):
        switch = Switch.objects.create(name='myswitch', active=False)
        assert not waffle.switch_is_active(switch.name)

    def test_switch_active_from_cache(self):
        """Do not make two queries for an existing active switch."""
        switch = Switch.objects.create(name='myswitch', active=True)
        # Get the value once so that it will be put into the cache
        assert waffle.switch_is_active(switch.name)
        queries = len(connection.queries)
        assert waffle.switch_is_active(switch.name)
        self.assertEqual(queries, len(connection.queries))

    def test_switch_inactive_from_cache(self):
        """Do not make two queries for an existing inactive switch."""
        switch = Switch.objects.create(name='myswitch', active=False)
        # Get the value once so that it will be put into the cache
        assert not waffle.switch_is_active(switch.name)
        queries = len(connection.queries)
        assert not waffle.switch_is_active(switch.name)
        self.assertEqual(queries, len(connection.queries))

    def test_undefined(self):
        assert not waffle.switch_is_active('foo')

    @override_settings(WAFFLE_SWITCH_DEFAULT=True)
    def test_undefined_default(self):
        assert waffle.switch_is_active('foo')

    @override_settings(DEBUG=True)
    def test_no_query(self):
        """Do not make two queries for a non-existent switch."""
        assert not Switch.objects.filter(name='foo').exists()
        queries = len(connection.queries)
        assert not waffle.switch_is_active('foo')
        assert len(connection.queries) > queries
        queries = len(connection.queries)
        assert not waffle.switch_is_active('foo')
        self.assertEqual(queries, len(connection.queries))

    @override_settings(DATABASE_ROUTERS=['waffle.tests.base.ReplicationRouter'])
    def test_read_from_write_db(self):
        switch = Switch.objects.create(name='switch', active=True)

        # By default, switch_is_active should hit whatever it configured as the
        # read DB (so values will be stale if replication is lagged).
        assert not waffle.switch_is_active(switch.name)

        with override_settings(WAFFLE_READ_FROM_WRITE_DB=True):
            # Save the switch again to flush the cache.
            switch.save()

            # The next read should now be directed to the write DB, ensuring
            # the cache and DB are in sync.
            assert waffle.switch_is_active(switch.name)


class SampleTests(TestCase):
    def test_sample_100(self):
        sample = Sample.objects.create(name='sample', percent='100.0')
        assert waffle.sample_is_active(sample.name)

    def test_sample_0(self):
        sample = Sample.objects.create(name='sample', percent='0.0')
        assert not waffle.sample_is_active(sample.name)

    def test_undefined(self):
        assert not waffle.sample_is_active('foo')

    @override_settings(WAFFLE_SAMPLE_DEFAULT=True)
    def test_undefined_default(self):
        assert waffle.sample_is_active('foo')

    @override_settings(DATABASE_ROUTERS=['waffle.tests.base.ReplicationRouter'])
    def test_read_from_write_db(self):
        sample = Sample.objects.create(name='sample', percent='100.0')

        # By default, sample_is_active should hit whatever it configured as the
        # read DB (so values will be stale if replication is lagged).
        assert not waffle.sample_is_active(sample.name)

        with override_settings(WAFFLE_READ_FROM_WRITE_DB=True):
            # Save the sample again to flush the cache.
            sample.save()

            # The next read should now be directed to the write DB, ensuring
            # the cache and DB are in sync.
            assert waffle.sample_is_active(sample.name)


class TransactionTests(TransactionTestCase):
    @unittest.skipIf('sqlite3' in settings.DATABASES['default']['ENGINE'],
                     'This test uses threads, which the sqlite3 DB engine '
                     'does not support.')
    def test_update_switch_in_transaction(self):
        """Wait to invalidate the cache until after the current transaction."""

        switch_name = 'transaction-switch-name'
        switch = Switch.objects.create(name=switch_name, active=False)
        self.addCleanup(switch.delete)

        switch_written_in_background_thread = threading.Event()
        switch_read_in_main_thread = threading.Event()

        @transaction.atomic
        def update_switch():
            switch.active = True
            switch.save()

            # Signal to the main thread that the switch has been updated, but
            # the transaction is not yet committed.
            switch_written_in_background_thread.set()

            # Pause here to allow the main thread to make an assertion.
            switch_read_in_main_thread.wait(timeout=1)

        # Start a background thread to update the switch in a transaction.
        t = threading.Thread(target=update_switch)
        t.daemon = True
        t.start()

        # After the switch is updated but before the transaction is committed,
        # the cache will still have the previous value.
        switch_written_in_background_thread.wait(timeout=1)
        assert not waffle.switch_is_active(switch_name)

        # After the transaction is committed, the cache should have been
        # invalidated, hence the next call to switch_is_active should have the
        # correct value.
        switch_read_in_main_thread.set()
        t.join(timeout=1)
        assert waffle.switch_is_active(switch_name)