From 919768c8bb3b5f1ab0cf084599c527eacaf82a29 Mon Sep 17 00:00:00 2001
From: Erik Kalkoken <erik.kalkoken@gmail.com>
Date: Fri, 17 Jun 2022 11:58:45 +0000
Subject: [PATCH] Fix: Broken docs generation on readthedocs.org (2nd attempt)

---
 .../task_statistics/event_series.py           | 49 ++++++++++++++++---
 .../tests/test_event_series.py                | 37 +++++++++++++-
 2 files changed, 78 insertions(+), 8 deletions(-)

diff --git a/allianceauth/authentication/task_statistics/event_series.py b/allianceauth/authentication/task_statistics/event_series.py
index f8591fbc..d1a222db 100644
--- a/allianceauth/authentication/task_statistics/event_series.py
+++ b/allianceauth/authentication/task_statistics/event_series.py
@@ -1,27 +1,62 @@
 import datetime as dt
-from typing import Optional, List
+import logging
+from typing import List, Optional
 
-from redis import Redis
 from pytz import utc
+from redis import Redis, RedisError
 
 from django.core.cache import cache
 
+logger = logging.getLogger(__name__)
+
+
+class _RedisStub:
+    """Stub of a Redis client.
+
+    It's purpose is to prevent EventSeries objects from trying to access Redis
+    when it is not available. e.g. when the Sphinx docs are rendered by readthedocs.org.
+    """
+
+    def delete(self, *args, **kwargs):
+        pass
+
+    def incr(self, *args, **kwargs):
+        return 0
+
+    def zadd(self, *args, **kwargs):
+        pass
+
+    def zcount(self, *args, **kwargs):
+        pass
+
+    def zrangebyscore(self, *args, **kwargs):
+        pass
+
 
 class EventSeries:
-    """API for recording and analysing a series of events."""
+    """API for recording and analyzing a series of events."""
 
     _ROOT_KEY = "ALLIANCEAUTH_EVENT_SERIES"
 
     def __init__(self, key_id: str, redis: Redis = None) -> None:
         self._redis = cache.get_master_client() if not redis else redis
-        if not isinstance(self._redis, Redis):
-            raise TypeError(
-                "This class requires a Redis client, but none was provided "
-                "and the default Django cache backend is not Redis either."
+        try:
+            if not self._redis.ping():
+                raise RuntimeError()
+        except (AttributeError, RedisError, RuntimeError):
+            logger.exception(
+                "Failed to establish a connection with Redis. "
+                "This EventSeries object is disabled.",
             )
+            self._redis = _RedisStub()
         self._key_id = str(key_id)
         self.clear()
 
+    @property
+    def is_disabled(self):
+        """True when this object is disabled, e.g. Redis was not available at startup."""
+        return isinstance(self._redis, _RedisStub)
+
     @property
     def _key_counter(self):
         return f"{self._ROOT_KEY}_{self._key_id}_COUNTER"
diff --git a/allianceauth/authentication/task_statistics/tests/test_event_series.py b/allianceauth/authentication/task_statistics/tests/test_event_series.py
index 079c4721..30b61465 100644
--- a/allianceauth/authentication/task_statistics/tests/test_event_series.py
+++ b/allianceauth/authentication/task_statistics/tests/test_event_series.py
@@ -1,13 +1,48 @@
 import datetime as dt
+from unittest.mock import patch
 
 from pytz import utc
+from redis import RedisError
+
 from django.test import TestCase
 from django.utils.timezone import now
 
-from allianceauth.authentication.task_statistics.event_series import EventSeries
+from allianceauth.authentication.task_statistics.event_series import (
+    EventSeries,
+    _RedisStub,
+)
+
+MODULE_PATH = "allianceauth.authentication.task_statistics.event_series"
 
 
 class TestEventSeries(TestCase):
+    def test_should_abort_without_redis_client(self):
+        # when
+        with patch(MODULE_PATH + ".cache.get_master_client") as mock:
+            mock.return_value = None
+            events = EventSeries("dummy")
+        # then
+        self.assertTrue(events._redis, _RedisStub)
+        self.assertTrue(events.is_disabled)
+
+    def test_should_disable_itself_if_redis_not_available_1(self):
+        # when
+        with patch(MODULE_PATH + ".cache.get_master_client") as mock_get_master_client:
+            mock_get_master_client.return_value.ping.side_effect = RedisError
+            events = EventSeries("dummy")
+        # then
+        self.assertIsInstance(events._redis, _RedisStub)
+        self.assertTrue(events.is_disabled)
+
+    def test_should_disable_itself_if_redis_not_available_2(self):
+        # when
+        with patch(MODULE_PATH + ".cache.get_master_client") as mock_get_master_client:
+            mock_get_master_client.return_value.ping.return_value = False
+            events = EventSeries("dummy")
+        # then
+        self.assertIsInstance(events._redis, _RedisStub)
+        self.assertTrue(events.is_disabled)
+
     def test_should_add_event(self):
         # given
         events = EventSeries("dummy")