Merge branch 'master' into whitelist_system

3 files changed, 946 insertions, 3 deletions

diff --git a/tests/bot/cogs/moderation/test_incidents.py b/tests/bot/cogs/moderation/test_incidents.py
new file mode 100644
index 000000000..435a1cd51
--- /dev/null
+++ b/tests/bot/cogs/moderation/test_incidents.py
@@ -0,0 +1,770 @@
+import asyncio
+import enum
+import logging
+import typing as t
+import unittest
+from unittest.mock import AsyncMock, MagicMock, call, patch
+
+import aiohttp
+import discord
+
+from bot.cogs.moderation import Incidents, incidents
+from bot.constants import Colours
+from tests.helpers import (
+    MockAsyncWebhook,
+    MockAttachment,
+    MockBot,
+    MockMember,
+    MockMessage,
+    MockReaction,
+    MockRole,
+    MockTextChannel,
+    MockUser,
+)
+
+
+class MockAsyncIterable:
+    """
+    Helper for mocking asynchronous for loops.
+
+    It does not appear that the `unittest` library currently provides anything that would
+    allow us to simply mock an async iterator, such as `discord.TextChannel.history`.
+
+    We therefore write our own helper to wrap a regular synchronous iterable, and feed
+    its values via `__anext__` rather than `__next__`.
+
+    This class was written for the purposes of testing the `Incidents` cog - it may not
+    be generic enough to be placed in the `tests.helpers` module.
+    """
+
+    def __init__(self, messages: t.Iterable):
+        """Take a sync iterable to be wrapped."""
+        self.iter_messages = iter(messages)
+
+    def __aiter__(self):
+        """Return `self` as we provide the `__anext__` method."""
+        return self
+
+    async def __anext__(self):
+        """
+        Feed the next item, or raise `StopAsyncIteration`.
+
+        Since we're wrapping a sync iterator, it will communicate that it has been depleted
+        by raising a `StopIteration`. The `async for` construct does not expect it, and we
+        therefore need to substitute it for the appropriate exception type.
+        """
+        try:
+            return next(self.iter_messages)
+        except StopIteration:
+            raise StopAsyncIteration
+
+
+class MockSignal(enum.Enum):
+    A = "A"
+    B = "B"
+
+
+mock_404 = discord.NotFound(
+    response=MagicMock(aiohttp.ClientResponse),  # Mock the erroneous response
+    message="Not found",
+)
+
+
+class TestDownloadFile(unittest.IsolatedAsyncioTestCase):
+    """Collection of tests for the `download_file` helper function."""
+
+    async def test_download_file_success(self):
+        """If `to_file` succeeds, function returns the acquired `discord.File`."""
+        file = MagicMock(discord.File, filename="bigbadlemon.jpg")
+        attachment = MockAttachment(to_file=AsyncMock(return_value=file))
+
+        acquired_file = await incidents.download_file(attachment)
+        self.assertIs(file, acquired_file)
+
+    async def test_download_file_404(self):
+        """If `to_file` encounters a 404, function handles the exception & returns None."""
+        attachment = MockAttachment(to_file=AsyncMock(side_effect=mock_404))
+
+        acquired_file = await incidents.download_file(attachment)
+        self.assertIsNone(acquired_file)
+
+    async def test_download_file_fail(self):
+        """If `to_file` fails on a non-404 error, function logs the exception & returns None."""
+        arbitrary_error = discord.HTTPException(MagicMock(aiohttp.ClientResponse), "Arbitrary API error")
+        attachment = MockAttachment(to_file=AsyncMock(side_effect=arbitrary_error))
+
+        with self.assertLogs(logger=incidents.log, level=logging.ERROR):
+            acquired_file = await incidents.download_file(attachment)
+
+        self.assertIsNone(acquired_file)
+
+
+class TestMakeEmbed(unittest.IsolatedAsyncioTestCase):
+    """Collection of tests for the `make_embed` helper function."""
+
+    async def test_make_embed_actioned(self):
+        """Embed is coloured green and footer contains 'Actioned' when `outcome=Signal.ACTIONED`."""
+        embed, file = await incidents.make_embed(MockMessage(), incidents.Signal.ACTIONED, MockMember())
+
+        self.assertEqual(embed.colour.value, Colours.soft_green)
+        self.assertIn("Actioned", embed.footer.text)
+
+    async def test_make_embed_not_actioned(self):
+        """Embed is coloured red and footer contains 'Rejected' when `outcome=Signal.NOT_ACTIONED`."""
+        embed, file = await incidents.make_embed(MockMessage(), incidents.Signal.NOT_ACTIONED, MockMember())
+
+        self.assertEqual(embed.colour.value, Colours.soft_red)
+        self.assertIn("Rejected", embed.footer.text)
+
+    async def test_make_embed_content(self):
+        """Incident content appears as embed description."""
+        incident = MockMessage(content="this is an incident")
+        embed, file = await incidents.make_embed(incident, incidents.Signal.ACTIONED, MockMember())
+
+        self.assertEqual(incident.content, embed.description)
+
+    async def test_make_embed_with_attachment_succeeds(self):
+        """Incident's attachment is downloaded and displayed in the embed's image field."""
+        file = MagicMock(discord.File, filename="bigbadjoe.jpg")
+        attachment = MockAttachment(filename="bigbadjoe.jpg")
+        incident = MockMessage(content="this is an incident", attachments=[attachment])
+
+        # Patch `download_file` to return our `file`
+        with patch("bot.cogs.moderation.incidents.download_file", AsyncMock(return_value=file)):
+            embed, returned_file = await incidents.make_embed(incident, incidents.Signal.ACTIONED, MockMember())
+
+        self.assertIs(file, returned_file)
+        self.assertEqual("attachment://bigbadjoe.jpg", embed.image.url)
+
+    async def test_make_embed_with_attachment_fails(self):
+        """Incident's attachment fails to download, proxy url is linked instead."""
+        attachment = MockAttachment(proxy_url="discord.com/bigbadjoe.jpg")
+        incident = MockMessage(content="this is an incident", attachments=[attachment])
+
+        # Patch `download_file` to return None as if the download failed
+        with patch("bot.cogs.moderation.incidents.download_file", AsyncMock(return_value=None)):
+            embed, returned_file = await incidents.make_embed(incident, incidents.Signal.ACTIONED, MockMember())
+
+        self.assertIsNone(returned_file)
+
+        # The author name field is simply expected to have something in it, we do not assert the message
+        self.assertGreater(len(embed.author.name), 0)
+        self.assertEqual(embed.author.url, "discord.com/bigbadjoe.jpg")  # However, it should link the exact url
+
+
+@patch("bot.constants.Channels.incidents", 123)
+class TestIsIncident(unittest.TestCase):
+    """
+    Collection of tests for the `is_incident` helper function.
+
+    In `setUp`, we will create a mock message which should qualify as an incident. Each
+    test case will then mutate this instance to make it **not** qualify, in various ways.
+
+    Notice that we patch the #incidents channel id globally for this class.
+    """
+
+    def setUp(self) -> None:
+        """Prepare a mock message which should qualify as an incident."""
+        self.incident = MockMessage(
+            channel=MockTextChannel(id=123),
+            content="this is an incident",
+            author=MockUser(bot=False),
+            pinned=False,
+        )
+
+    def test_is_incident_true(self):
+        """Message qualifies as an incident if unchanged."""
+        self.assertTrue(incidents.is_incident(self.incident))
+
+    def check_false(self):
+        """Assert that `self.incident` does **not** qualify as an incident."""
+        self.assertFalse(incidents.is_incident(self.incident))
+
+    def test_is_incident_false_channel(self):
+        """Message doesn't qualify if sent outside of #incidents."""
+        self.incident.channel = MockTextChannel(id=456)
+        self.check_false()
+
+    def test_is_incident_false_content(self):
+        """Message doesn't qualify if content begins with hash symbol."""
+        self.incident.content = "# this is a comment message"
+        self.check_false()
+
+    def test_is_incident_false_author(self):
+        """Message doesn't qualify if author is a bot."""
+        self.incident.author = MockUser(bot=True)
+        self.check_false()
+
+    def test_is_incident_false_pinned(self):
+        """Message doesn't qualify if it is pinned."""
+        self.incident.pinned = True
+        self.check_false()
+
+
+class TestOwnReactions(unittest.TestCase):
+    """Assertions for the `own_reactions` function."""
+
+    def test_own_reactions(self):
+        """Only bot's own emoji are extracted from the input incident."""
+        reactions = (
+            MockReaction(emoji="A", me=True),
+            MockReaction(emoji="B", me=True),
+            MockReaction(emoji="C", me=False),
+        )
+        message = MockMessage(reactions=reactions)
+        self.assertSetEqual(incidents.own_reactions(message), {"A", "B"})
+
+
+@patch("bot.cogs.moderation.incidents.ALL_SIGNALS", {"A", "B"})
+class TestHasSignals(unittest.TestCase):
+    """
+    Assertions for the `has_signals` function.
+
+    We patch `ALL_SIGNALS` globally. Each test function then patches `own_reactions`
+    as appropriate.
+    """
+
+    def test_has_signals_true(self):
+        """True when `own_reactions` returns all emoji in `ALL_SIGNALS`."""
+        message = MockMessage()
+        own_reactions = MagicMock(return_value={"A", "B"})
+
+        with patch("bot.cogs.moderation.incidents.own_reactions", own_reactions):
+            self.assertTrue(incidents.has_signals(message))
+
+    def test_has_signals_false(self):
+        """False when `own_reactions` does not return all emoji in `ALL_SIGNALS`."""
+        message = MockMessage()
+        own_reactions = MagicMock(return_value={"A", "C"})
+
+        with patch("bot.cogs.moderation.incidents.own_reactions", own_reactions):
+            self.assertFalse(incidents.has_signals(message))
+
+
+@patch("bot.cogs.moderation.incidents.Signal", MockSignal)
+class TestAddSignals(unittest.IsolatedAsyncioTestCase):
+    """
+    Assertions for the `add_signals` coroutine.
+
+    These are all fairly similar and could go into a single test function, but I found the
+    patching & sub-testing fairly awkward in that case and decided to split them up
+    to avoid unnecessary syntax noise.
+    """
+
+    def setUp(self):
+        """Prepare a mock incident message for tests to use."""
+        self.incident = MockMessage()
+
+    @patch("bot.cogs.moderation.incidents.own_reactions", MagicMock(return_value=set()))
+    async def test_add_signals_missing(self):
+        """All emoji are added when none are present."""
+        await incidents.add_signals(self.incident)
+        self.incident.add_reaction.assert_has_calls([call("A"), call("B")])
+
+    @patch("bot.cogs.moderation.incidents.own_reactions", MagicMock(return_value={"A"}))
+    async def test_add_signals_partial(self):
+        """Only missing emoji are added when some are present."""
+        await incidents.add_signals(self.incident)
+        self.incident.add_reaction.assert_has_calls([call("B")])
+
+    @patch("bot.cogs.moderation.incidents.own_reactions", MagicMock(return_value={"A", "B"}))
+    async def test_add_signals_present(self):
+        """No emoji are added when all are present."""
+        await incidents.add_signals(self.incident)
+        self.incident.add_reaction.assert_not_called()
+
+
+class TestIncidents(unittest.IsolatedAsyncioTestCase):
+    """
+    Tests for bound methods of the `Incidents` cog.
+
+    Use this as a base class for `Incidents` tests - it will prepare a fresh instance
+    for each test function, but not make any assertions on its own. Tests can mutate
+    the instance as they wish.
+    """
+
+    def setUp(self):
+        """
+        Prepare a fresh `Incidents` instance for each test.
+
+        Note that this will not schedule `crawl_incidents` in the background, as everything
+        is being mocked. The `crawl_task` attribute will end up being None.
+        """
+        self.cog_instance = Incidents(MockBot())
+
+
+@patch("asyncio.sleep", AsyncMock())  # Prevent the coro from sleeping to speed up the test
+class TestCrawlIncidents(TestIncidents):
+    """
+    Tests for the `Incidents.crawl_incidents` coroutine.
+
+    Apart from `test_crawl_incidents_waits_until_cache_ready`, all tests in this class
+    will patch the return values of `is_incident` and `has_signal` and then observe
+    whether the `AsyncMock` for `add_signals` was awaited or not.
+
+    The `add_signals` mock is added by each test separately to ensure it is clean (has not
+    been awaited by another test yet). The mock can be reset, but this appears to be the
+    cleaner way.
+
+    For each test, we inject a mock channel with a history of 1 message only (see: `setUp`).
+    """
+
+    def setUp(self):
+        """For each test, ensure `bot.get_channel` returns a channel with 1 arbitrary message."""
+        super().setUp()  # First ensure we get `cog_instance` from parent
+
+        incidents_history = MagicMock(return_value=MockAsyncIterable([MockMessage()]))
+        self.cog_instance.bot.get_channel = MagicMock(return_value=MockTextChannel(history=incidents_history))
+
+    async def test_crawl_incidents_waits_until_cache_ready(self):
+        """
+        The coroutine will await the `wait_until_guild_available` event.
+
+        Since this task is schedule in the `__init__`, it is critical that it waits for the
+        cache to be ready, so that it can safely get the #incidents channel.
+        """
+        await self.cog_instance.crawl_incidents()
+        self.cog_instance.bot.wait_until_guild_available.assert_awaited()
+
+    @patch("bot.cogs.moderation.incidents.add_signals", AsyncMock())
+    @patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=False))  # Message doesn't qualify
+    @patch("bot.cogs.moderation.incidents.has_signals", MagicMock(return_value=False))
+    async def test_crawl_incidents_noop_if_is_not_incident(self):
+        """Signals are not added for a non-incident message."""
+        await self.cog_instance.crawl_incidents()
+        incidents.add_signals.assert_not_awaited()
+
+    @patch("bot.cogs.moderation.incidents.add_signals", AsyncMock())
+    @patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=True))  # Message qualifies
+    @patch("bot.cogs.moderation.incidents.has_signals", MagicMock(return_value=True))  # But already has signals
+    async def test_crawl_incidents_noop_if_message_already_has_signals(self):
+        """Signals are not added for messages which already have them."""
+        await self.cog_instance.crawl_incidents()
+        incidents.add_signals.assert_not_awaited()
+
+    @patch("bot.cogs.moderation.incidents.add_signals", AsyncMock())
+    @patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=True))  # Message qualifies
+    @patch("bot.cogs.moderation.incidents.has_signals", MagicMock(return_value=False))  # And doesn't have signals
+    async def test_crawl_incidents_add_signals_called(self):
+        """Message has signals added as it does not have them yet and qualifies as an incident."""
+        await self.cog_instance.crawl_incidents()
+        incidents.add_signals.assert_awaited_once()
+
+
+class TestArchive(TestIncidents):
+    """Tests for the `Incidents.archive` coroutine."""
+
+    async def test_archive_webhook_not_found(self):
+        """
+        Method recovers and returns False when the webhook is not found.
+
+        Implicitly, this also tests that the error is handled internally and doesn't
+        propagate out of the method, which is just as important.
+        """
+        self.cog_instance.bot.fetch_webhook = AsyncMock(side_effect=mock_404)
+        self.assertFalse(
+            await self.cog_instance.archive(incident=MockMessage(), outcome=MagicMock(), actioned_by=MockMember())
+        )
+
+    async def test_archive_relays_incident(self):
+        """
+        If webhook is found, method relays `incident` properly.
+
+        This test will assert that the fetched webhook's `send` method is fed the correct arguments,
+        and that the `archive` method returns True.
+        """
+        webhook = MockAsyncWebhook()
+        self.cog_instance.bot.fetch_webhook = AsyncMock(return_value=webhook)  # Patch in our webhook
+
+        # Define our own `incident` to be archived
+        incident = MockMessage(
+            content="this is an incident",
+            author=MockUser(name="author_name", avatar_url="author_avatar"),
+            id=123,
+        )
+        built_embed = MagicMock(discord.Embed, id=123)  # We patch `make_embed` to return this
+
+        with patch("bot.cogs.moderation.incidents.make_embed", AsyncMock(return_value=(built_embed, None))):
+            archive_return = await self.cog_instance.archive(incident, MagicMock(value="A"), MockMember())
+
+        # Now we check that the webhook was given the correct args, and that `archive` returned True
+        webhook.send.assert_called_once_with(
+            embed=built_embed,
+            username="author_name",
+            avatar_url="author_avatar",
+            file=None,
+        )
+        self.assertTrue(archive_return)
+
+    async def test_archive_clyde_username(self):
+        """
+        The archive webhook username is cleansed using `sub_clyde`.
+
+        Discord will reject any webhook with "clyde" in the username field, as it impersonates
+        the official Clyde bot. Since we do not control what the username will be (the incident
+        author name is used), we must ensure the name is cleansed, otherwise the relay may fail.
+
+        This test assumes the username is passed as a kwarg. If this test fails, please review
+        whether the passed argument is being retrieved correctly.
+        """
+        webhook = MockAsyncWebhook()
+        self.cog_instance.bot.fetch_webhook = AsyncMock(return_value=webhook)
+
+        message_from_clyde = MockMessage(author=MockUser(name="clyde the great"))
+        await self.cog_instance.archive(message_from_clyde, MagicMock(incidents.Signal), MockMember())
+
+        self.assertNotIn("clyde", webhook.send.call_args.kwargs["username"])
+
+
+class TestMakeConfirmationTask(TestIncidents):
+    """
+    Tests for the `Incidents.make_confirmation_task` method.
+
+    Writing tests for this method is difficult, as it mostly just delegates the provided
+    information elsewhere. There is very little internal logic. Whether our approach
+    works conceptually is difficult to prove using unit tests.
+    """
+
+    def test_make_confirmation_task_check(self):
+        """
+        The internal check will recognize the passed incident.
+
+        This is a little tricky - we first pass a message with a specific `id` in, and then
+        retrieve the built check from the `call_args` of the `wait_for` method. This relies
+        on the check being passed as a kwarg.
+
+        Once the check is retrieved, we assert that it gives True for our incident's `id`,
+        and False for any other.
+
+        If this function begins to fail, first check that `created_check` is being retrieved
+        correctly. It should be the function that is built locally in the tested method.
+        """
+        self.cog_instance.make_confirmation_task(MockMessage(id=123))
+
+        self.cog_instance.bot.wait_for.assert_called_once()
+        created_check = self.cog_instance.bot.wait_for.call_args.kwargs["check"]
+
+        # The `message_id` matches the `id` of our incident
+        self.assertTrue(created_check(payload=MagicMock(message_id=123)))
+
+        # This `message_id` does not match
+        self.assertFalse(created_check(payload=MagicMock(message_id=0)))
+
+
+@patch("bot.cogs.moderation.incidents.ALLOWED_ROLES", {1, 2})
+@patch("bot.cogs.moderation.incidents.Incidents.make_confirmation_task", AsyncMock())  # Generic awaitable
+class TestProcessEvent(TestIncidents):
+    """Tests for the `Incidents.process_event` coroutine."""
+
+    async def test_process_event_bad_role(self):
+        """The reaction is removed when the author lacks all allowed roles."""
+        incident = MockMessage()
+        member = MockMember(roles=[MockRole(id=0)])  # Must have role 1 or 2
+
+        await self.cog_instance.process_event("reaction", incident, member)
+        incident.remove_reaction.assert_called_once_with("reaction", member)
+
+    async def test_process_event_bad_emoji(self):
+        """
+        The reaction is removed when an invalid emoji is used.
+
+        This requires that we pass in a `member` with valid roles, as we need the role check
+        to succeed.
+        """
+        incident = MockMessage()
+        member = MockMember(roles=[MockRole(id=1)])  # Member has allowed role
+
+        await self.cog_instance.process_event("invalid_signal", incident, member)
+        incident.remove_reaction.assert_called_once_with("invalid_signal", member)
+
+    async def test_process_event_no_archive_on_investigating(self):
+        """Message is not archived on `Signal.INVESTIGATING`."""
+        with patch("bot.cogs.moderation.incidents.Incidents.archive", AsyncMock()) as mocked_archive:
+            await self.cog_instance.process_event(
+                reaction=incidents.Signal.INVESTIGATING.value,
+                incident=MockMessage(),
+                member=MockMember(roles=[MockRole(id=1)]),
+            )
+
+        mocked_archive.assert_not_called()
+
+    async def test_process_event_no_delete_if_archive_fails(self):
+        """
+        Original message is not deleted when `Incidents.archive` returns False.
+
+        This is the way of signaling that the relay failed, and we should not remove the original,
+        as that would result in losing the incident record.
+        """
+        incident = MockMessage()
+
+        with patch("bot.cogs.moderation.incidents.Incidents.archive", AsyncMock(return_value=False)):
+            await self.cog_instance.process_event(
+                reaction=incidents.Signal.ACTIONED.value,
+                incident=incident,
+                member=MockMember(roles=[MockRole(id=1)])
+            )
+
+        incident.delete.assert_not_called()
+
+    async def test_process_event_confirmation_task_is_awaited(self):
+        """Task given by `Incidents.make_confirmation_task` is awaited before method exits."""
+        mock_task = AsyncMock()
+
+        with patch("bot.cogs.moderation.incidents.Incidents.make_confirmation_task", mock_task):
+            await self.cog_instance.process_event(
+                reaction=incidents.Signal.ACTIONED.value,
+                incident=MockMessage(),
+                member=MockMember(roles=[MockRole(id=1)])
+            )
+
+        mock_task.assert_awaited()
+
+    async def test_process_event_confirmation_task_timeout_is_handled(self):
+        """
+        Confirmation task `asyncio.TimeoutError` is handled gracefully.
+
+        We have `make_confirmation_task` return a mock with a side effect, and then catch the
+        exception should it propagate out of `process_event`. This is so that we can then manually
+        fail the test with a more informative message than just the plain traceback.
+        """
+        mock_task = AsyncMock(side_effect=asyncio.TimeoutError())
+
+        try:
+            with patch("bot.cogs.moderation.incidents.Incidents.make_confirmation_task", mock_task):
+                await self.cog_instance.process_event(
+                    reaction=incidents.Signal.ACTIONED.value,
+                    incident=MockMessage(),
+                    member=MockMember(roles=[MockRole(id=1)])
+                )
+        except asyncio.TimeoutError:
+            self.fail("TimeoutError was not handled gracefully, and propagated out of `process_event`!")
+
+
+class TestResolveMessage(TestIncidents):
+    """Tests for the `Incidents.resolve_message` coroutine."""
+
+    async def test_resolve_message_pass_message_id(self):
+        """Method will call `_get_message` with the passed `message_id`."""
+        await self.cog_instance.resolve_message(123)
+        self.cog_instance.bot._connection._get_message.assert_called_once_with(123)
+
+    async def test_resolve_message_in_cache(self):
+        """
+        No API call is made if the queried message exists in the cache.
+
+        We mock the `_get_message` return value regardless of input. Whether it finds the message
+        internally is considered d.py's responsibility, not ours.
+        """
+        cached_message = MockMessage(id=123)
+        self.cog_instance.bot._connection._get_message = MagicMock(return_value=cached_message)
+
+        return_value = await self.cog_instance.resolve_message(123)
+
+        self.assertIs(return_value, cached_message)
+        self.cog_instance.bot.get_channel.assert_not_called()  # The `fetch_message` line was never hit
+
+    async def test_resolve_message_not_in_cache(self):
+        """
+        The message is retrieved from the API if it isn't cached.
+
+        This is desired behaviour for messages which exist, but were sent before the bot's
+        current session.
+        """
+        self.cog_instance.bot._connection._get_message = MagicMock(return_value=None)  # Cache returns None
+
+        # API returns our message
+        uncached_message = MockMessage()
+        fetch_message = AsyncMock(return_value=uncached_message)
+        self.cog_instance.bot.get_channel = MagicMock(return_value=MockTextChannel(fetch_message=fetch_message))
+
+        retrieved_message = await self.cog_instance.resolve_message(123)
+        self.assertIs(retrieved_message, uncached_message)
+
+    async def test_resolve_message_doesnt_exist(self):
+        """
+        If the API returns a 404, the function handles it gracefully and returns None.
+
+        This is an edge-case happening with racing events - event A will relay the message
+        to the archive and delete the original. Once event B acquires the `event_lock`,
+        it will not find the message in the cache, and will ask the API.
+        """
+        self.cog_instance.bot._connection._get_message = MagicMock(return_value=None)  # Cache returns None
+
+        fetch_message = AsyncMock(side_effect=mock_404)
+        self.cog_instance.bot.get_channel = MagicMock(return_value=MockTextChannel(fetch_message=fetch_message))
+
+        self.assertIsNone(await self.cog_instance.resolve_message(123))
+
+    async def test_resolve_message_fetch_fails(self):
+        """
+        Non-404 errors are handled, logged & None is returned.
+
+        In contrast with a 404, this should make an error-level log. We assert that at least
+        one such log was made - we do not make any assertions about the log's message.
+        """
+        self.cog_instance.bot._connection._get_message = MagicMock(return_value=None)  # Cache returns None
+
+        arbitrary_error = discord.HTTPException(
+            response=MagicMock(aiohttp.ClientResponse),
+            message="Arbitrary error",
+        )
+        fetch_message = AsyncMock(side_effect=arbitrary_error)
+        self.cog_instance.bot.get_channel = MagicMock(return_value=MockTextChannel(fetch_message=fetch_message))
+
+        with self.assertLogs(logger=incidents.log, level=logging.ERROR):
+            self.assertIsNone(await self.cog_instance.resolve_message(123))
+
+
+@patch("bot.constants.Channels.incidents", 123)
+class TestOnRawReactionAdd(TestIncidents):
+    """
+    Tests for the `Incidents.on_raw_reaction_add` listener.
+
+    Writing tests for this listener comes with additional complexity due to the listener
+    awaiting the `crawl_task` task. See `asyncSetUp` for further details, which attempts
+    to make unit testing this function possible.
+    """
+
+    def setUp(self):
+        """
+        Prepare & assign `payload` attribute.
+
+        This attribute represents an *ideal* payload which will not be rejected by the
+        listener. As each test will receive a fresh instance, it can be mutated to
+        observe how the listener's behaviour changes with different attributes on
+        the passed payload.
+        """
+        super().setUp()  # Ensure `cog_instance` is assigned
+
+        self.payload = MagicMock(
+            discord.RawReactionActionEvent,
+            channel_id=123,  # Patched at class level
+            message_id=456,
+            member=MockMember(bot=False),
+            emoji="reaction",
+        )
+
+    async def asyncSetUp(self):  # noqa: N802
+        """
+        Prepare an empty task and assign it as `crawl_task`.
+
+        It appears that the `unittest` framework does not provide anything for mocking
+        asyncio tasks. An `AsyncMock` instance can be called and then awaited, however,
+        it does not provide the `done` method or any other parts of the `asyncio.Task`
+        interface.
+
+        Although we do not need to make any assertions about the task itself while
+        testing the listener, the code will still await it and call the `done` method,
+        and so we must inject something that will not fail on either action.
+
+        Note that this is done in an `asyncSetUp`, which runs after `setUp`.
+        The justification is that creating an actual task requires the event
+        loop to be ready, which is not the case in the `setUp`.
+        """
+        mock_task = asyncio.create_task(AsyncMock()())  # Mock async func, then a coro
+        self.cog_instance.crawl_task = mock_task
+
+    async def test_on_raw_reaction_add_wrong_channel(self):
+        """
+        Events outside of #incidents will be ignored.
+
+        We check this by asserting that `resolve_message` was never queried.
+        """
+        self.payload.channel_id = 0
+        self.cog_instance.resolve_message = AsyncMock()
+
+        await self.cog_instance.on_raw_reaction_add(self.payload)
+        self.cog_instance.resolve_message.assert_not_called()
+
+    async def test_on_raw_reaction_add_user_is_bot(self):
+        """
+        Events dispatched by bot accounts will be ignored.
+
+        We check this by asserting that `resolve_message` was never queried.
+        """
+        self.payload.member = MockMember(bot=True)
+        self.cog_instance.resolve_message = AsyncMock()
+
+        await self.cog_instance.on_raw_reaction_add(self.payload)
+        self.cog_instance.resolve_message.assert_not_called()
+
+    async def test_on_raw_reaction_add_message_doesnt_exist(self):
+        """
+        Listener gracefully handles the case where `resolve_message` gives None.
+
+        We check this by asserting that `process_event` was never called.
+        """
+        self.cog_instance.process_event = AsyncMock()
+        self.cog_instance.resolve_message = AsyncMock(return_value=None)
+
+        await self.cog_instance.on_raw_reaction_add(self.payload)
+        self.cog_instance.process_event.assert_not_called()
+
+    async def test_on_raw_reaction_add_message_is_not_an_incident(self):
+        """
+        The event won't be processed if the related message is not an incident.
+
+        This is an edge-case that can happen if someone manually leaves a reaction
+        on a pinned message, or a comment.
+
+        We check this by asserting that `process_event` was never called.
+        """
+        self.cog_instance.process_event = AsyncMock()
+        self.cog_instance.resolve_message = AsyncMock(return_value=MockMessage())
+
+        with patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=False)):
+            await self.cog_instance.on_raw_reaction_add(self.payload)
+
+        self.cog_instance.process_event.assert_not_called()
+
+    async def test_on_raw_reaction_add_valid_event_is_processed(self):
+        """
+        If the reaction event is valid, it is passed to `process_event`.
+
+        This is the case when everything goes right:
+            * The reaction was placed in #incidents, and not by a bot
+            * The message was found successfully
+            * The message qualifies as an incident
+
+        Additionally, we check that all arguments were passed as expected.
+        """
+        incident = MockMessage(id=1)
+
+        self.cog_instance.process_event = AsyncMock()
+        self.cog_instance.resolve_message = AsyncMock(return_value=incident)
+
+        with patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=True)):
+            await self.cog_instance.on_raw_reaction_add(self.payload)
+
+        self.cog_instance.process_event.assert_called_with(
+            "reaction",  # Defined in `self.payload`
+            incident,
+            self.payload.member,
+        )
+
+
+class TestOnMessage(TestIncidents):
+    """
+    Tests for the `Incidents.on_message` listener.
+
+    Notice the decorators mocking the `is_incident` return value. The `is_incidents`
+    function is tested in `TestIsIncident` - here we do not worry about it.
+    """
+
+    @patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=True))
+    async def test_on_message_incident(self):
+        """Messages qualifying as incidents are passed to `add_signals`."""
+        incident = MockMessage()
+
+        with patch("bot.cogs.moderation.incidents.add_signals", AsyncMock()) as mock_add_signals:
+            await self.cog_instance.on_message(incident)
+
+        mock_add_signals.assert_called_once_with(incident)
+
+    @patch("bot.cogs.moderation.incidents.is_incident", MagicMock(return_value=False))
+    async def test_on_message_non_incident(self):
+        """Messages not qualifying as incidents are ignored."""
+        with patch("bot.cogs.moderation.incidents.add_signals", AsyncMock()) as mock_add_signals:
+            await self.cog_instance.on_message(MockMessage())
+
+        mock_add_signals.assert_not_called()
diff --git a/tests/bot/cogs/test_jams.py b/tests/bot/cogs/test_jams.py
new file mode 100644
index 000000000..b4ad8535f
--- /dev/null
+++ b/tests/bot/cogs/test_jams.py
@@ -0,0 +1,173 @@
+import unittest
+from unittest.mock import AsyncMock, MagicMock, create_autospec
+
+from discord import CategoryChannel
+
+from bot.cogs import jams
+from bot.constants import Roles
+from tests.helpers import MockBot, MockContext, MockGuild, MockMember, MockRole, MockTextChannel
+
+
+def get_mock_category(channel_count: int, name: str) -> CategoryChannel:
+    """Return a mocked code jam category."""
+    category = create_autospec(CategoryChannel, spec_set=True, instance=True)
+    category.name = name
+    category.channels = [MockTextChannel() for _ in range(channel_count)]
+
+    return category
+
+
+class JamCreateTeamTests(unittest.IsolatedAsyncioTestCase):
+    """Tests for `createteam` command."""
+
+    def setUp(self):
+        self.bot = MockBot()
+        self.admin_role = MockRole(name="Admins", id=Roles.admins)
+        self.command_user = MockMember([self.admin_role])
+        self.guild = MockGuild([self.admin_role])
+        self.ctx = MockContext(bot=self.bot, author=self.command_user, guild=self.guild)
+        self.cog = jams.CodeJams(self.bot)
+
+    async def test_too_small_amount_of_team_members_passed(self):
+        """Should `ctx.send` and exit early when too small amount of members."""
+        for case in (1, 2):
+            with self.subTest(amount_of_members=case):
+                self.cog.create_channels = AsyncMock()
+                self.cog.add_roles = AsyncMock()
+
+                self.ctx.reset_mock()
+                members = (MockMember() for _ in range(case))
+                await self.cog.createteam(self.cog, self.ctx, "foo", members)
+
+                self.ctx.send.assert_awaited_once()
+                self.cog.create_channels.assert_not_awaited()
+                self.cog.add_roles.assert_not_awaited()
+
+    async def test_duplicate_members_provided(self):
+        """Should `ctx.send` and exit early because duplicate members provided and total there is only 1 member."""
+        self.cog.create_channels = AsyncMock()
+        self.cog.add_roles = AsyncMock()
+
+        member = MockMember()
+        await self.cog.createteam(self.cog, self.ctx, "foo", (member for _ in range(5)))
+
+        self.ctx.send.assert_awaited_once()
+        self.cog.create_channels.assert_not_awaited()
+        self.cog.add_roles.assert_not_awaited()
+
+    async def test_result_sending(self):
+        """Should call `ctx.send` when everything goes right."""
+        self.cog.create_channels = AsyncMock()
+        self.cog.add_roles = AsyncMock()
+
+        members = [MockMember() for _ in range(5)]
+        await self.cog.createteam(self.cog, self.ctx, "foo", members)
+
+        self.cog.create_channels.assert_awaited_once()
+        self.cog.add_roles.assert_awaited_once()
+        self.ctx.send.assert_awaited_once()
+
+    async def test_category_doesnt_exist(self):
+        """Should create a new code jam category."""
+        subtests = (
+            [],
+            [get_mock_category(jams.MAX_CHANNELS - 1, jams.CATEGORY_NAME)],
+            [get_mock_category(jams.MAX_CHANNELS - 2, "other")],
+        )
+
+        for categories in subtests:
+            self.guild.reset_mock()
+            self.guild.categories = categories
+
+            with self.subTest(categories=categories):
+                actual_category = await self.cog.get_category(self.guild)
+
+                self.guild.create_category_channel.assert_awaited_once()
+                category_overwrites = self.guild.create_category_channel.call_args[1]["overwrites"]
+
+                self.assertFalse(category_overwrites[self.guild.default_role].read_messages)
+                self.assertTrue(category_overwrites[self.guild.me].read_messages)
+                self.assertEqual(self.guild.create_category_channel.return_value, actual_category)
+
+    async def test_category_channel_exist(self):
+        """Should not try to create category channel."""
+        expected_category = get_mock_category(jams.MAX_CHANNELS - 2, jams.CATEGORY_NAME)
+        self.guild.categories = [
+            get_mock_category(jams.MAX_CHANNELS - 2, "other"),
+            expected_category,
+            get_mock_category(0, jams.CATEGORY_NAME),
+        ]
+
+        actual_category = await self.cog.get_category(self.guild)
+        self.assertEqual(expected_category, actual_category)
+
+    async def test_channel_overwrites(self):
+        """Should have correct permission overwrites for users and roles."""
+        leader = MockMember()
+        members = [leader] + [MockMember() for _ in range(4)]
+        overwrites = self.cog.get_overwrites(members, self.guild)
+
+        # Leader permission overwrites
+        self.assertTrue(overwrites[leader].manage_messages)
+        self.assertTrue(overwrites[leader].read_messages)
+        self.assertTrue(overwrites[leader].manage_webhooks)
+        self.assertTrue(overwrites[leader].connect)
+
+        # Other members permission overwrites
+        for member in members[1:]:
+            self.assertTrue(overwrites[member].read_messages)
+            self.assertTrue(overwrites[member].connect)
+
+        # Everyone and verified role overwrite
+        self.assertFalse(overwrites[self.guild.default_role].read_messages)
+        self.assertFalse(overwrites[self.guild.default_role].connect)
+        self.assertFalse(overwrites[self.guild.get_role(Roles.verified)].read_messages)
+        self.assertFalse(overwrites[self.guild.get_role(Roles.verified)].connect)
+
+    async def test_team_channels_creation(self):
+        """Should create new voice and text channel for team."""
+        members = [MockMember() for _ in range(5)]
+
+        self.cog.get_overwrites = MagicMock()
+        self.cog.get_category = AsyncMock()
+        self.ctx.guild.create_text_channel.return_value = MockTextChannel(mention="foobar-channel")
+        actual = await self.cog.create_channels(self.guild, "my-team", members)
+
+        self.assertEqual("foobar-channel", actual)
+        self.cog.get_overwrites.assert_called_once_with(members, self.guild)
+        self.cog.get_category.assert_awaited_once_with(self.guild)
+
+        self.guild.create_text_channel.assert_awaited_once_with(
+            "my-team",
+            overwrites=self.cog.get_overwrites.return_value,
+            category=self.cog.get_category.return_value
+        )
+        self.guild.create_voice_channel.assert_awaited_once_with(
+            "My Team",
+            overwrites=self.cog.get_overwrites.return_value,
+            category=self.cog.get_category.return_value
+        )
+
+    async def test_jam_roles_adding(self):
+        """Should add team leader role to leader and jam role to every team member."""
+        leader_role = MockRole(name="Team Leader")
+        jam_role = MockRole(name="Jammer")
+        self.guild.get_role.side_effect = [leader_role, jam_role]
+
+        leader = MockMember()
+        members = [leader] + [MockMember() for _ in range(4)]
+        await self.cog.add_roles(self.guild, members)
+
+        leader.add_roles.assert_any_await(leader_role)
+        for member in members:
+            member.add_roles.assert_any_await(jam_role)
+
+
+class CodeJamSetup(unittest.TestCase):
+    """Test for `setup` function of `CodeJam` cog."""
+
+    def test_setup(self):
+        """Should call `bot.add_cog`."""
+        bot = MockBot()
+        jams.setup(bot)
+        bot.add_cog.assert_called_once()
diff --git a/tests/bot/cogs/test_snekbox.py b/tests/bot/cogs/test_snekbox.py
index 98dee7a1b..343e37db9 100644
--- a/tests/bot/cogs/test_snekbox.py
+++ b/tests/bot/cogs/test_snekbox.py
@@ -239,7 +239,7 @@ class SnekboxTests(unittest.IsolatedAsyncioTestCase):
 
         await self.cog.send_eval(ctx, 'MyAwesomeCode')
         ctx.send.assert_called_once_with(
-            '@LemonLemonishBeard#0042 :yay!: Return code 0.\n\n```py\n[No output]\n```'
+            '@LemonLemonishBeard#0042 :yay!: Return code 0.\n\n```\n[No output]\n```'
         )
         self.cog.post_eval.assert_called_once_with('MyAwesomeCode')
         self.cog.get_status_emoji.assert_called_once_with({'stdout': '', 'returncode': 0})
@@ -265,7 +265,7 @@ class SnekboxTests(unittest.IsolatedAsyncioTestCase):
         await self.cog.send_eval(ctx, 'MyAwesomeCode')
         ctx.send.assert_called_once_with(
             '@LemonLemonishBeard#0042 :yay!: Return code 0.'
-            '\n\n```py\nWay too long beard\n```\nFull output: lookatmybeard.com'
+            '\n\n```\nWay too long beard\n```\nFull output: lookatmybeard.com'
         )
         self.cog.post_eval.assert_called_once_with('MyAwesomeCode')
         self.cog.get_status_emoji.assert_called_once_with({'stdout': 'Way too long beard', 'returncode': 0})
@@ -289,7 +289,7 @@ class SnekboxTests(unittest.IsolatedAsyncioTestCase):
 
         await self.cog.send_eval(ctx, 'MyAwesomeCode')
         ctx.send.assert_called_once_with(
-            '@LemonLemonishBeard#0042 :nope!: Return code 127.\n\n```py\nBeard got stuck in the eval\n```'
+            '@LemonLemonishBeard#0042 :nope!: Return code 127.\n\n```\nBeard got stuck in the eval\n```'
         )
         self.cog.post_eval.assert_called_once_with('MyAwesomeCode')
         self.cog.get_status_emoji.assert_called_once_with({'stdout': 'ERROR', 'returncode': 127})