Add an option to use fakeredis in Bot.

Without this option, all contributors would need to set up a Redis
server in order to run the bot. But with use_fakeredis set to True, this
is no longer necessary because it will just set up a fakeredis redis
pool instead of trying to contact an actual server.

This is more than good enough for most local testing purposes, since
data persistence across restarts isn't really relevant for them.

This also means we need to move fakeredis into our real dependency list
instead of having it as a dev dependency, so there's a minor change for
that as well.

I also made a small kaizen change to sort all the dependencies in the
Pipfile alphabetically.

5 files changed, 66 insertions, 48 deletions

diff --git a/Pipfile b/Pipfile
index cd2f2ad7a..b42ca6d58 100644
--- a/Pipfile
+++ b/Pipfile
@@ -4,30 +4,30 @@ verify_ssl = true
 name = "pypi"
 
 [packages]
-discord.py = "~=1.3.2"
+aio-pika = "~=6.1"
 aiodns = "~=2.0"
 aiohttp = "~=3.5"
-sphinx = "~=2.2"
-markdownify = "~=0.4"
-lxml = "~=4.4"
-pyyaml = "~=5.1"
+aioredis = "~=1.3.1"
+beautifulsoup4 = "~=4.9"
+colorama = {version = "~=0.4.3",sys_platform = "== 'win32'"}
+coloredlogs = "~=14.0"
+deepdiff = "~=4.0"
+discord.py = "~=1.3.2"
+fakeredis = "~=1.4"
+feedparser = "~=5.2"
 fuzzywuzzy = "~=0.17"
-aio-pika = "~=6.1"
+lxml = "~=4.4"
+markdownify = "~=0.4"
+more_itertools = "~=8.2"
 python-dateutil = "~=2.8"
-deepdiff = "~=4.0"
+pyyaml = "~=5.1"
 requests = "~=2.22"
-more_itertools = "~=8.2"
 sentry-sdk = "~=0.14"
-coloredlogs = "~=14.0"
-colorama = {version = "~=0.4.3",sys_platform = "== 'win32'"}
+sphinx = "~=2.2"
 statsd = "~=3.3"
-feedparser = "~=5.2"
-beautifulsoup4 = "~=4.9"
-aioredis = "~=1.3.1"
 
 [dev-packages]
 coverage = "~=5.0"
-fakeredis = "~=1.4"
 flake8 = "~=3.7"
 flake8-annotations = "~=2.0"
 flake8-bugbear = "~=20.1"
diff --git a/Pipfile.lock b/Pipfile.lock
index 1941f6887..0e591710c 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "c0b3e4d3e2c9ddb6ba28d2c09d521fe90ad4ea3df5c7ea7cd3a8b679fb3f85f9"
+            "sha256": "0297accc3d614d3da8080b89d56ef7fe489c28a0ada8102df396a604af7ee330"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -196,6 +196,14 @@
             ],
             "version": "==0.16"
         },
+        "fakeredis": {
+            "hashes": [
+                "sha256:4d170886865a91dbc8b7f8cbd4e5d488f4c5f2f25dfae127f001617bbe9e8f97",
+                "sha256:647b2593d349d9d4e566c8dadb2e4c71ba35be5bdc4f1f7ac2d565a12a965053"
+            ],
+            "index": "pypi",
+            "version": "==1.4.1"
+        },
         "feedparser": {
             "hashes": [
                 "sha256:bd030652c2d08532c034c27fcd7c85868e7fa3cb2b17f230a44a6bbc92519bf9",
@@ -501,6 +509,13 @@
             "index": "pypi",
             "version": "==5.3.1"
         },
+        "redis": {
+            "hashes": [
+                "sha256:2ef11f489003f151777c064c5dbc6653dfb9f3eade159bcadc524619fddc2242",
+                "sha256:6d65e84bc58091140081ee9d9c187aab0480097750fac44239307a3bdf0b1251"
+            ],
+            "version": "==3.5.2"
+        },
         "requests": {
             "hashes": [
                 "sha256:43999036bfa82904b6af1d99e4882b560e5e2c68e5c4b0aa03b655f3d7d73fee",
@@ -531,6 +546,13 @@
             ],
             "version": "==2.0.0"
         },
+        "sortedcontainers": {
+            "hashes": [
+                "sha256:974e9a32f56b17c1bac2aebd9dcf197f3eb9cd30553c5852a3187ad162e1a03a",
+                "sha256:d9e96492dd51fae31e60837736b38fe42a187b5404c16606ff7ee7cd582d4c60"
+            ],
+            "version": "==2.1.0"
+        },
         "soupsieve": {
             "hashes": [
                 "sha256:1634eea42ab371d3d346309b93df7870a88610f0725d47528be902a0d95ecc55",
@@ -718,14 +740,6 @@
             ],
             "version": "==0.3.0"
         },
-        "fakeredis": {
-            "hashes": [
-                "sha256:4d170886865a91dbc8b7f8cbd4e5d488f4c5f2f25dfae127f001617bbe9e8f97",
-                "sha256:647b2593d349d9d4e566c8dadb2e4c71ba35be5bdc4f1f7ac2d565a12a965053"
-            ],
-            "index": "pypi",
-            "version": "==1.4.1"
-        },
         "filelock": {
             "hashes": [
                 "sha256:18d82244ee114f543149c66a6e0c14e9c4f8a1044b5cdaadd0f82159d6a6ff59",
@@ -735,11 +749,11 @@
         },
         "flake8": {
             "hashes": [
-                "sha256:6c1193b0c3f853ef763969238f6c81e9e63ace9d024518edc020d5f1d6d93195",
-                "sha256:ea6623797bf9a52f4c9577d780da0bb17d65f870213f7b5bcc9fca82540c31d5"
+                "sha256:c69ac1668e434d37a2d2880b3ca9aafd54b3a10a3ac1ab101d22f29e29cf8634",
+                "sha256:ccaa799ef9893cebe69fdfefed76865aeaefbb94cb8545617b2298786a4de9a5"
             ],
             "index": "pypi",
-            "version": "==3.8.1"
+            "version": "==3.8.2"
         },
         "flake8-annotations": {
             "hashes": [
@@ -805,10 +819,10 @@
         },
         "identify": {
             "hashes": [
-                "sha256:23c18d97bb50e05be1a54917ee45cc61d57cb96aedc06aabb2b02331edf0dbf0",
-                "sha256:88ed90632023e52a6495749c6732e61e08ec9f4f04e95484a5c37b9caf40283c"
+                "sha256:0f3c3aac62b51b86fea6ff52fe8ff9e06f57f10411502443809064d23e16f1c2",
+                "sha256:f9ad3d41f01e98eb066b6e05c5b184fd1e925fadec48eb165b4e01c72a1ef3a7"
             ],
-            "version": "==1.4.15"
+            "version": "==1.4.16"
         },
         "mccabe": {
             "hashes": [
@@ -877,13 +891,6 @@
             "index": "pypi",
             "version": "==5.3.1"
         },
-        "redis": {
-            "hashes": [
-                "sha256:2ef11f489003f151777c064c5dbc6653dfb9f3eade159bcadc524619fddc2242",
-                "sha256:6d65e84bc58091140081ee9d9c187aab0480097750fac44239307a3bdf0b1251"
-            ],
-            "version": "==3.5.2"
-        },
         "six": {
             "hashes": [
                 "sha256:30639c035cdb23534cd4aa2dd52c3bf48f06e5f4a941509c8bafd8ce11080259",
@@ -898,13 +905,6 @@
             ],
             "version": "==2.0.0"
         },
-        "sortedcontainers": {
-            "hashes": [
-                "sha256:974e9a32f56b17c1bac2aebd9dcf197f3eb9cd30553c5852a3187ad162e1a03a",
-                "sha256:d9e96492dd51fae31e60837736b38fe42a187b5404c16606ff7ee7cd582d4c60"
-            ],
-            "version": "==2.1.0"
-        },
         "toml": {
             "hashes": [
                 "sha256:926b612be1e5ce0634a2ca03470f95169cf16f939018233a670519cb4ac58b0f",
diff --git a/bot/bot.py b/bot/bot.py
index 0d423201b..f1365d532 100644
--- a/bot/bot.py
+++ b/bot/bot.py
@@ -7,6 +7,7 @@ from typing import Optional
 import aiohttp
 import aioredis
 import discord
+import fakeredis.aioredis
 from discord.ext import commands
 from sentry_sdk import push_scope
 
@@ -48,11 +49,26 @@ class Bot(commands.Bot):
         self.stats = AsyncStatsClient(self.loop, statsd_url, 8125, prefix="bot")
 
     async def _create_redis_session(self) -> None:
-        """Create the Redis connection pool, and then open the redis event gate."""
-        self.redis_session = await aioredis.create_redis_pool(
-            address=(constants.Redis.host, constants.Redis.port),
-            password=constants.Redis.password,
-        )
+        """
+        Create the Redis connection pool, and then open the redis event gate.
+
+        If constants.Redis.use_fakeredis is True, we'll set up a fake redis pool instead
+        of attempting to communicate with a real Redis server. This is useful because it
+        means contributors don't necessarily need to get Redis running locally just
+        to run the bot.
+
+        The fakeredis cache won't have persistence across restarts, but that
+        usually won't matter for local bot testing.
+        """
+        if constants.Redis.use_fakeredis:
+            log.info("Using fakeredis instead of communicating with a real Redis server.")
+            self.redis_session = await fakeredis.aioredis.create_redis_pool()
+        else:
+            self.redis_session = await aioredis.create_redis_pool(
+                address=(constants.Redis.host, constants.Redis.port),
+                password=constants.Redis.password,
+            )
+
         self.redis_ready.set()
 
     def add_cog(self, cog: commands.Cog) -> None:
diff --git a/bot/constants.py b/bot/constants.py
index 5d854dd7a..75d394b6a 100644
--- a/bot/constants.py
+++ b/bot/constants.py
@@ -208,6 +208,7 @@ class Redis(metaclass=YAMLGetter):
     host: str
     port: int
     password: str
+    use_fakeredis: bool  # If this is True, Bot will use fakeredis.aioredis
 
 
 class Filter(metaclass=YAMLGetter):
diff --git a/config-default.yml b/config-default.yml
index 5be393463..cee955f20 100644
--- a/config-default.yml
+++ b/config-default.yml
@@ -7,6 +7,7 @@ bot:
         host:  "redis"
         port:  6379
         password: !ENV "REDIS_PASSWORD"
+        use_fakeredis: false
 
     stats:
         statsd_host: "graphite"