Lazy Man's Django test case

"""
Decrease the verbosity of writing view tests.

Old way:

    self.client.get(reverse("my-view"))
    self.client.post(reverse("my-view"), data={"key": "value"})
    self.client.login("username", "password")
    self.client.get(reverse("my-other-view"))
    self.client.logout()

    self.client.post(reverse("my-other-view"), data={"key": "value"}
    self.assertEqual(response.status_code, 302)
    self.assertEqual(response["Location"], "http://remoteserver/")

    session = self.client.session
    session["key"] = "value"
    session.save()

New way:

    self.client.get("my-view")
    self.client.post("my-view", data={"key": "value"})
    with self.login("username", "password"):
        self.client.get("my-other-view")

    self.assertRedirectsTo(response, "http://remoteserver/")

    session = self.session
    session["key"] = "value"
    session.save()

By default also patches the template loader and initiates the client session.
"""

from django.conf import settings
from django.core.urlresolvers import reverse
from django.template import Template
from django.test import TestCase
from django.utils.importlib import import_module
import django.template.loader


class login(object):
    def __init__(self, testcase, user, password):
        self.testcase = testcase
        success = testcase.client.login(username=user, password=password)
        self.testcase.assertTrue(
            success,
            "login with username=%r, password=%r failed" % (user, password)
        )

    def __enter__(self):
        pass

    def __exit__(self, *args):
        self.testcase.client.logout()


class LazyTestCase(TestCase):
    patch_templates = True

    def login(self, user, password):
        return login(self, user, password)

    def get(self, url_name, data=None, *args, **kwargs):
        data = data or {}
        return self.client.get(
            reverse(url_name, args=args, kwargs=kwargs), data
        )

    def post(self, url_name, data=None, *args, **kwargs):
        return self.client.post(
            reverse(url_name, args=args, kwargs=kwargs), data
        )

    @property
    def session(self):
        return self.client.session

    def load_data(self):
        return

    def setUp(self):
        if self.patch_templates:
            self.get_template = django.template.loader.get_template
            def get_template(*args, **kwargs):
                return Template("")
            django.template.loader.get_template = get_template

        if "django.contrib.sessions" in settings.INSTALLED_APPS:
            # Workaround for https://code.djangoproject.com/ticket/15740
            engine = import_module(settings.SESSION_ENGINE)
            store = engine.SessionStore()
            store.save()
            self.client.cookies[settings.SESSION_COOKIE_NAME] = store.session_key

        self.load_data()

    def tearDown(self):
        if self.patch_templates:
            django.template.loader.get_template = self.get_template

    def assertRedirectsTo(self, response, url):
        """
        Assert that a response redirects to a specific url without trying to
        load the other page.
        """
        self.assertEqual(response.status_code, 302)
        self.assertEqual(response["Location"], url)