Merge pull request #37 from percipient/override-settings

Allow settings to be overridden.

django_slack/api.py

@@ -2,15 +2,16 @@
 
 from django.conf import settings
 from django.template.loader import render_to_string
-from django.utils.module_loading import import_string
 
-from . import app_settings
+from .utils import get_backend
+from .app_settings import app_settings
 
-backend = import_string(app_settings.BACKEND)()
-
-def slack_message(template, context=None, attachments=None, fail_silently=app_settings.FAIL_SILENTLY):
+def slack_message(template, context=None, attachments=None, fail_silently=None):
+    backend = get_backend()
     data = {}
     context = dict(context or {}, settings=settings)
+    if fail_silently is None:
+        fail_silently = app_settings.FAIL_SILENTLY
 
     for k, v in {
         'text': {

django_slack/app_settings.py

@@ -1,20 +1,26 @@
 from django.conf import settings
 
-DEFAULT_ENDPOINT_URL = 'https://slack.com/api/chat.postMessage'
+class AppSettings(object):
+    # Lazily obtain settings to support ``override_settings`` decorator
+    def get(suffix, default):
+        def setting(self):
+            return getattr(settings, 'SLACK_%s' % suffix, default)
+        return setting
 
-def setting(suffix, default):
-    return getattr(settings, 'SLACK_%s' % suffix, default)
+    TOKEN = property(get('TOKEN', None))
+    CHANNEL = property(get('CHANNEL', '#general'))
+    USERNAME = property(get('USERNAME', 'bot'))
+    ICON_URL = property(get('ICON_URL', None))
+    ICON_EMOJI = property(get('ICON_EMOJI', None))
 
-TOKEN = setting('TOKEN', None)
-CHANNEL = setting('CHANNEL', '#general')
-USERNAME = setting('USERNAME', 'bot')
-ICON_URL = setting('ICON_URL', None)
-ICON_EMOJI = setting('ICON_EMOJI', None)
-ENDPOINT_URL = setting('ENDPOINT_URL', DEFAULT_ENDPOINT_URL)
+    DEFAULT_ENDPOINT_URL = 'https://slack.com/api/chat.postMessage'
+    ENDPOINT_URL = property(get('ENDPOINT_URL', DEFAULT_ENDPOINT_URL))
 
-_BACKEND = 'django_slack.backends.DisabledBackend' if settings.DEBUG else \
-    'django_slack.backends.UrllibBackend'
-BACKEND = setting('BACKEND', _BACKEND)
-BACKEND_FOR_QUEUE = setting('BACKEND_FOR_QUEUE', _BACKEND)
+    _DEFAULT_BACKEND = 'django_slack.backends.DisabledBackend' if settings.DEBUG else \
+        'django_slack.backends.UrllibBackend'
+    BACKEND = property(get('BACKEND', _DEFAULT_BACKEND))
+    BACKEND_FOR_QUEUE = property(get('BACKEND_FOR_QUEUE', _DEFAULT_BACKEND))
 
-FAIL_SILENTLY = setting('FAIL_SILENTLY', False)
+    FAIL_SILENTLY = property(get('FAIL_SILENTLY', False))
+
+app_settings = AppSettings()

django_slack/backends.py

@@ -4,8 +4,8 @@
 
 from django.utils.module_loading import import_string
 
-from . import app_settings
 from .utils import Backend
+from .app_settings import app_settings
 
 class UrllibBackend(Backend):
     def send(self, url, data):

django_slack/utils.py

@@ -1,5 +1,9 @@
 import json
 
+from django.utils.module_loading import import_string
+
+from .app_settings import app_settings
+
 class Backend(object):
     def send(self, url, data):
         raise NotImplementedError()
@@ -13,3 +17,13 @@ def validate(self, content_type, content):
 
         elif content != 'ok':
             raise ValueError(content)
+
+def get_backend():
+    """
+    Wrap the backend in a function to not load it at import time.
+    get_backend() caches the backend on first call.
+    """
+    if get_backend.backend is None:
+        get_backend.backend = import_string(app_settings.BACKEND)()
+    return get_backend.backend
+get_backend.backend = None

tests/backends.py

@@ -19,3 +19,13 @@ def send(self, url, data):
             'url': url,
             'data': data,
         })
+
+class RaisingBackend(Backend):
+    """
+    A backend which raises when asked to send a message.
+    """
+    class RaisedException(Exception):
+        pass
+
+    def send(self, url, data):
+        raise RaisingBackend.RaisedException(url, data)

tests/settings.py

@@ -1,5 +1,12 @@
 SECRET_KEY = 'not_empty'
 
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.sqlite3',
+        'NAME': ':memory:',
+    }
+}
+
 TEMPLATES = [
     {
         'BACKEND': 'django.template.backends.django.DjangoTemplates',

tests/test_escaping.py

@@ -1,22 +1,23 @@
 import unittest
 
 from django_slack import slack_message
-from django_slack.api import backend
+from django_slack.utils import get_backend
 
 class SlackTestCase(unittest.TestCase):
     def setUp(self):
-        backend.reset()
+        self.backend = get_backend()
+        self.backend.reset()
 
     def assertMessageCount(self, count):
-        self.assertEqual(len(backend.messages), count)
+        self.assertEqual(len(self.backend.messages), count)
 
     def assertMessage(self, url=None, **kwargs):
         """
         Ensure there was only one message sent with a URL and data values.
         """
 
         self.assertMessageCount(1)
-        message = backend.messages[0]
+        message = self.backend.messages[0]
 
         # Optionally ensure the URL.
         if url is not None:

tests/test_override.py

@@ -0,0 +1,47 @@
+from django.conf import settings
+from django.test import TestCase, override_settings
+
+from django_slack import slack_message
+from django_slack.utils import get_backend
+from django_slack.app_settings import app_settings
+
+from tests.backends import RaisingBackend
+
+class TestOverride(TestCase):
+    def setUp(self):
+        # Fake the backend not having been initialized yet.
+        get_backend.backend = None
+
+    def test_override(self):
+        """
+        Ensure that accessing a setting in an override works.
+        """
+        DISABLED_BACKEND = 'django_slack.backends.DisabledBackend'
+        with override_settings(SLACK_BACKEND=DISABLED_BACKEND):
+            self.assertEqual(settings.SLACK_BACKEND, DISABLED_BACKEND)
+            self.assertEqual(app_settings.BACKEND, DISABLED_BACKEND)
+
+    def test_backend_cache(self):
+        """
+        Ensure that the backend is cached once it is called once.
+        """
+        self.assertEqual(id(get_backend()), id(get_backend()))
+
+    def test_backend_override(self):
+        """
+        Ensure the backend can be overridden.
+        """
+        with override_settings(SLACK_BACKEND='tests.backends.RaisingBackend'):
+            with self.assertRaises(RaisingBackend.RaisedException):
+                slack_message('test.slack', {'text': 'test'})
+
+    def test_fail_silently(self):
+        """
+        Ensure fail silently can be overridden.
+        """
+        # Note that this will fail if test_backend_override ever fails.
+        with override_settings(
+            SLACK_FAIL_SILENTLY=True,
+            SLACK_BACKEND='tests.backends.RaisingBackend',
+        ):
+            slack_message('test.slack', {'text': 'test'})