Merge branch 'master' into message-edit-hyperlink

7 files changed, 1185 insertions, 20 deletions

diff --git a/tests/bot/cogs/test_duck_pond.py b/tests/bot/cogs/test_duck_pond.py
new file mode 100644
index 000000000..b801e86f1
--- /dev/null
+++ b/tests/bot/cogs/test_duck_pond.py
@@ -0,0 +1,592 @@
+import asyncio
+import logging
+import typing
+import unittest
+from unittest.mock import MagicMock, patch
+
+import discord
+
+from bot import constants
+from bot.cogs import duck_pond
+from tests import base
+from tests import helpers
+
+MODULE_PATH = "bot.cogs.duck_pond"
+
+
+class DuckPondTests(base.LoggingTestCase):
+    """Tests for DuckPond functionality."""
+
+    @classmethod
+    def setUpClass(cls):
+        """Sets up the objects that only have to be initialized once."""
+        cls.nonstaff_member = helpers.MockMember(name="Non-staffer")
+
+        cls.staff_role = helpers.MockRole(name="Staff role", id=constants.STAFF_ROLES[0])
+        cls.staff_member = helpers.MockMember(name="staffer", roles=[cls.staff_role])
+
+        cls.checkmark_emoji = "\N{White Heavy Check Mark}"
+        cls.thumbs_up_emoji = "\N{Thumbs Up Sign}"
+        cls.unicode_duck_emoji = "\N{Duck}"
+        cls.duck_pond_emoji = helpers.MockPartialEmoji(id=constants.DuckPond.custom_emojis[0])
+        cls.non_duck_custom_emoji = helpers.MockPartialEmoji(id=123)
+
+    def setUp(self):
+        """Sets up the objects that need to be refreshed before each test."""
+        self.bot = helpers.MockBot(user=helpers.MockMember(id=46692))
+        self.cog = duck_pond.DuckPond(bot=self.bot)
+
+    def test_duck_pond_correctly_initializes(self):
+        """`__init__ should set `bot` and `webhook_id` attributes and schedule `fetch_webhook`."""
+        bot = helpers.MockBot()
+        cog = MagicMock()
+
+        duck_pond.DuckPond.__init__(cog, bot)
+
+        self.assertEqual(cog.bot, bot)
+        self.assertEqual(cog.webhook_id, constants.Webhooks.duck_pond)
+        bot.loop.create_loop.called_once_with(cog.fetch_webhook())
+
+    def test_fetch_webhook_succeeds_without_connectivity_issues(self):
+        """The `fetch_webhook` method waits until `READY` event and sets the `webhook` attribute."""
+        self.bot.fetch_webhook.return_value = "dummy webhook"
+        self.cog.webhook_id = 1
+
+        asyncio.run(self.cog.fetch_webhook())
+
+        self.bot.wait_until_ready.assert_called_once()
+        self.bot.fetch_webhook.assert_called_once_with(1)
+        self.assertEqual(self.cog.webhook, "dummy webhook")
+
+    def test_fetch_webhook_logs_when_unable_to_fetch_webhook(self):
+        """The `fetch_webhook` method should log an exception when it fails to fetch the webhook."""
+        self.bot.fetch_webhook.side_effect = discord.HTTPException(response=MagicMock(), message="Not found.")
+        self.cog.webhook_id = 1
+
+        log = logging.getLogger('bot.cogs.duck_pond')
+        with self.assertLogs(logger=log, level=logging.ERROR) as log_watcher:
+            asyncio.run(self.cog.fetch_webhook())
+
+        self.bot.wait_until_ready.assert_called_once()
+        self.bot.fetch_webhook.assert_called_once_with(1)
+
+        self.assertEqual(len(log_watcher.records), 1)
+
+        record = log_watcher.records[0]
+        self.assertEqual(record.levelno, logging.ERROR)
+
+    def test_is_staff_returns_correct_values_based_on_instance_passed(self):
+        """The `is_staff` method should return correct values based on the instance passed."""
+        test_cases = (
+            (helpers.MockUser(name="User instance"), False),
+            (helpers.MockMember(name="Member instance without staff role"), False),
+            (helpers.MockMember(name="Member instance with staff role", roles=[self.staff_role]), True)
+        )
+
+        for user, expected_return in test_cases:
+            actual_return = self.cog.is_staff(user)
+            with self.subTest(user_type=user.name, expected_return=expected_return, actual_return=actual_return):
+                self.assertEqual(expected_return, actual_return)
+
+    @helpers.async_test
+    async def test_has_green_checkmark_correctly_detects_presence_of_green_checkmark_emoji(self):
+        """The `has_green_checkmark` method should only return `True` if one is present."""
+        test_cases = (
+            (
+                "No reactions", helpers.MockMessage(), False
+            ),
+            (
+                "No green check mark reactions",
+                helpers.MockMessage(reactions=[
+                    helpers.MockReaction(emoji=self.unicode_duck_emoji, users=[self.bot.user]),
+                    helpers.MockReaction(emoji=self.thumbs_up_emoji, users=[self.bot.user])
+                ]),
+                False
+            ),
+            (
+                "Green check mark reaction, but not from our bot",
+                helpers.MockMessage(reactions=[
+                    helpers.MockReaction(emoji=self.unicode_duck_emoji, users=[self.bot.user]),
+                    helpers.MockReaction(emoji=self.checkmark_emoji, users=[self.staff_member])
+                ]),
+                False
+            ),
+            (
+                "Green check mark reaction, with one from the bot",
+                helpers.MockMessage(reactions=[
+                    helpers.MockReaction(emoji=self.unicode_duck_emoji, users=[self.bot.user]),
+                    helpers.MockReaction(emoji=self.checkmark_emoji, users=[self.staff_member, self.bot.user])
+                ]),
+                True
+            )
+        )
+
+        for description, message, expected_return in test_cases:
+            actual_return = await self.cog.has_green_checkmark(message)
+            with self.subTest(
+                test_case=description,
+                expected_return=expected_return,
+                actual_return=actual_return
+            ):
+                self.assertEqual(expected_return, actual_return)
+
+    def test_send_webhook_correctly_passes_on_arguments(self):
+        """The `send_webhook` method should pass the arguments to the webhook correctly."""
+        self.cog.webhook = helpers.MockAsyncWebhook()
+
+        content = "fake content"
+        username = "fake username"
+        avatar_url = "fake avatar_url"
+        embed = "fake embed"
+
+        asyncio.run(self.cog.send_webhook(content, username, avatar_url, embed))
+
+        self.cog.webhook.send.assert_called_once_with(
+            content=content,
+            username=username,
+            avatar_url=avatar_url,
+            embed=embed
+        )
+
+    def test_send_webhook_logs_when_sending_message_fails(self):
+        """The `send_webhook` method should catch a `discord.HTTPException` and log accordingly."""
+        self.cog.webhook = helpers.MockAsyncWebhook()
+        self.cog.webhook.send.side_effect = discord.HTTPException(response=MagicMock(), message="Something failed.")
+
+        log = logging.getLogger('bot.cogs.duck_pond')
+        with self.assertLogs(logger=log, level=logging.ERROR) as log_watcher:
+            asyncio.run(self.cog.send_webhook())
+
+        self.assertEqual(len(log_watcher.records), 1)
+
+        record = log_watcher.records[0]
+        self.assertEqual(record.levelno, logging.ERROR)
+
+    def _get_reaction(
+        self,
+        emoji: typing.Union[str, helpers.MockEmoji],
+        staff: int = 0,
+        nonstaff: int = 0
+    ) -> helpers.MockReaction:
+        staffers = [helpers.MockMember(roles=[self.staff_role]) for _ in range(staff)]
+        nonstaffers = [helpers.MockMember() for _ in range(nonstaff)]
+        return helpers.MockReaction(emoji=emoji, users=staffers + nonstaffers)
+
+    @helpers.async_test
+    async def test_count_ducks_correctly_counts_the_number_of_eligible_duck_emojis(self):
+        """The `count_ducks` method should return the number of unique staffers who gave a duck."""
+        test_cases = (
+            # Simple test cases
+            # A message without reactions should return 0
+            (
+                "No reactions",
+                helpers.MockMessage(),
+                0
+            ),
+            # A message with a non-duck reaction from a non-staffer should return 0
+            (
+                "Non-duck reaction from non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.thumbs_up_emoji, nonstaff=1)]),
+                0
+            ),
+            # A message with a non-duck reaction from a staffer should return 0
+            (
+                "Non-duck reaction from staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.non_duck_custom_emoji, staff=1)]),
+                0
+            ),
+            # A message with a non-duck reaction from a non-staffer and staffer should return 0
+            (
+                "Non-duck reaction from staffer + non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.thumbs_up_emoji, staff=1, nonstaff=1)]),
+                0
+            ),
+            # A message with a unicode duck reaction from a non-staffer should return 0
+            (
+                "Unicode Duck Reaction from non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.unicode_duck_emoji, nonstaff=1)]),
+                0
+            ),
+            # A message with a unicode duck reaction from a staffer should return 1
+            (
+                "Unicode Duck Reaction from staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.unicode_duck_emoji, staff=1)]),
+                1
+            ),
+            # A message with a unicode duck reaction from a non-staffer and staffer should return 1
+            (
+                "Unicode Duck Reaction from staffer + non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.unicode_duck_emoji, staff=1, nonstaff=1)]),
+                1
+            ),
+            # A message with a duckpond duck reaction from a non-staffer should return 0
+            (
+                "Duckpond Duck Reaction from non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.duck_pond_emoji, nonstaff=1)]),
+                0
+            ),
+            # A message with a duckpond duck reaction from a staffer should return 1
+            (
+                "Duckpond Duck Reaction from staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.duck_pond_emoji, staff=1)]),
+                1
+            ),
+            # A message with a duckpond duck reaction from a non-staffer and staffer should return 1
+            (
+                "Duckpond Duck Reaction from staffer + non-staffer",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.duck_pond_emoji, staff=1, nonstaff=1)]),
+                1
+            ),
+
+            # Complex test cases
+            # A message with duckpond duck reactions from 3 staffers and 2 non-staffers returns 3
+            (
+                "Duckpond Duck Reaction from 3 staffers + 2 non-staffers",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=self.duck_pond_emoji, staff=3, nonstaff=2)]),
+                3
+            ),
+            # A staffer with multiple duck reactions only counts once
+            (
+                "Two different duck reactions from the same staffer",
+                helpers.MockMessage(
+                    reactions=[
+                        helpers.MockReaction(emoji=self.duck_pond_emoji, users=[self.staff_member]),
+                        helpers.MockReaction(emoji=self.unicode_duck_emoji, users=[self.staff_member]),
+                    ]
+                ),
+                1
+            ),
+            # A non-string emoji does not count (to test the `isinstance(reaction.emoji, str)` elif)
+            (
+                "Reaction with non-Emoji/str emoij from 3 staffers + 2 non-staffers",
+                helpers.MockMessage(reactions=[self._get_reaction(emoji=100, staff=3, nonstaff=2)]),
+                0
+            ),
+            # We correctly sum when multiple reactions are provided.
+            (
+                "Duckpond Duck Reaction from 3 staffers + 2 non-staffers",
+                helpers.MockMessage(
+                    reactions=[
+                        self._get_reaction(emoji=self.duck_pond_emoji, staff=3, nonstaff=2),
+                        self._get_reaction(emoji=self.unicode_duck_emoji, staff=4, nonstaff=9),
+                    ]
+                ),
+                3 + 4
+            ),
+        )
+
+        for description, message, expected_count in test_cases:
+            actual_count = await self.cog.count_ducks(message)
+            with self.subTest(test_case=description, expected_count=expected_count, actual_count=actual_count):
+                self.assertEqual(expected_count, actual_count)
+
+    @helpers.async_test
+    async def test_relay_message_correctly_relays_content_and_attachments(self):
+        """The `relay_message` method should correctly relay message content and attachments."""
+        send_webhook_path = f"{MODULE_PATH}.DuckPond.send_webhook"
+        send_attachments_path = f"{MODULE_PATH}.send_attachments"
+
+        self.cog.webhook = helpers.MockAsyncWebhook()
+
+        test_values = (
+            (helpers.MockMessage(clean_content="", attachments=[]), False, False),
+            (helpers.MockMessage(clean_content="message", attachments=[]), True, False),
+            (helpers.MockMessage(clean_content="", attachments=["attachment"]), False, True),
+            (helpers.MockMessage(clean_content="message", attachments=["attachment"]), True, True),
+        )
+
+        for message, expect_webhook_call, expect_attachment_call in test_values:
+            with patch(send_webhook_path, new_callable=helpers.AsyncMock) as send_webhook:
+                with patch(send_attachments_path, new_callable=helpers.AsyncMock) as send_attachments:
+                    with self.subTest(clean_content=message.clean_content, attachments=message.attachments):
+                        await self.cog.relay_message(message)
+
+                        self.assertEqual(expect_webhook_call, send_webhook.called)
+                        self.assertEqual(expect_attachment_call, send_attachments.called)
+
+                        message.add_reaction.assert_called_once_with(self.checkmark_emoji)
+
+    @patch(f"{MODULE_PATH}.send_attachments", new_callable=helpers.AsyncMock)
+    @helpers.async_test
+    async def test_relay_message_handles_irretrievable_attachment_exceptions(self, send_attachments):
+        """The `relay_message` method should handle irretrievable attachments."""
+        message = helpers.MockMessage(clean_content="message", attachments=["attachment"])
+        side_effects = (discord.errors.Forbidden(MagicMock(), ""), discord.errors.NotFound(MagicMock(), ""))
+
+        self.cog.webhook = helpers.MockAsyncWebhook()
+        log = logging.getLogger("bot.cogs.duck_pond")
+
+        for side_effect in side_effects:
+            send_attachments.side_effect = side_effect
+            with patch(f"{MODULE_PATH}.DuckPond.send_webhook", new_callable=helpers.AsyncMock) as send_webhook:
+                with self.subTest(side_effect=type(side_effect).__name__):
+                    with self.assertNotLogs(logger=log, level=logging.ERROR):
+                        await self.cog.relay_message(message)
+
+                    self.assertEqual(send_webhook.call_count, 2)
+
+    @patch(f"{MODULE_PATH}.DuckPond.send_webhook", new_callable=helpers.AsyncMock)
+    @patch(f"{MODULE_PATH}.send_attachments", new_callable=helpers.AsyncMock)
+    @helpers.async_test
+    async def test_relay_message_handles_attachment_http_error(self, send_attachments, send_webhook):
+        """The `relay_message` method should handle irretrievable attachments."""
+        message = helpers.MockMessage(clean_content="message", attachments=["attachment"])
+
+        self.cog.webhook = helpers.MockAsyncWebhook()
+        log = logging.getLogger("bot.cogs.duck_pond")
+
+        side_effect = discord.HTTPException(MagicMock(), "")
+        send_attachments.side_effect = side_effect
+        with self.subTest(side_effect=type(side_effect).__name__):
+            with self.assertLogs(logger=log, level=logging.ERROR) as log_watcher:
+                await self.cog.relay_message(message)
+
+            send_webhook.assert_called_once_with(
+                content=message.clean_content,
+                username=message.author.display_name,
+                avatar_url=message.author.avatar_url
+            )
+
+            self.assertEqual(len(log_watcher.records), 1)
+
+            record = log_watcher.records[0]
+            self.assertEqual(record.levelno, logging.ERROR)
+
+    def _mock_payload(self, label: str, is_custom_emoji: bool, id_: int, emoji_name: str):
+        """Creates a mock `on_raw_reaction_add` payload with the specified emoji data."""
+        payload = MagicMock(name=label)
+        payload.emoji.is_custom_emoji.return_value = is_custom_emoji
+        payload.emoji.id = id_
+        payload.emoji.name = emoji_name
+        return payload
+
+    @helpers.async_test
+    async def test_payload_has_duckpond_emoji_correctly_detects_relevant_emojis(self):
+        """The `on_raw_reaction_add` event handler should ignore irrelevant emojis."""
+        test_values = (
+            # Custom Emojis
+            (
+                self._mock_payload(
+                    label="Custom Duckpond Emoji",
+                    is_custom_emoji=True,
+                    id_=constants.DuckPond.custom_emojis[0],
+                    emoji_name=""
+                ),
+                True
+            ),
+            (
+                self._mock_payload(
+                    label="Custom Non-Duckpond Emoji",
+                    is_custom_emoji=True,
+                    id_=123,
+                    emoji_name=""
+                ),
+                False
+            ),
+            # Unicode Emojis
+            (
+                self._mock_payload(
+                    label="Unicode Duck Emoji",
+                    is_custom_emoji=False,
+                    id_=1,
+                    emoji_name=self.unicode_duck_emoji
+                ),
+                True
+            ),
+            (
+                self._mock_payload(
+                    label="Unicode Non-Duck Emoji",
+                    is_custom_emoji=False,
+                    id_=1,
+                    emoji_name=self.thumbs_up_emoji
+                ),
+                False
+            ),
+        )
+
+        for payload, expected_return in test_values:
+            actual_return = self.cog._payload_has_duckpond_emoji(payload)
+            with self.subTest(case=payload._mock_name, expected_return=expected_return, actual_return=actual_return):
+                self.assertEqual(expected_return, actual_return)
+
+    @patch(f"{MODULE_PATH}.discord.utils.get")
+    @patch(f"{MODULE_PATH}.DuckPond._payload_has_duckpond_emoji", new=MagicMock(return_value=False))
+    def test_on_raw_reaction_add_returns_early_with_payload_without_duck_emoji(self, utils_get):
+        """The `on_raw_reaction_add` method should return early if the payload does not contain a duck emoji."""
+        self.assertIsNone(asyncio.run(self.cog.on_raw_reaction_add(payload=MagicMock())))
+
+        # Ensure we've returned before making an unnecessary API call in the lines of code after the emoji check
+        utils_get.assert_not_called()
+
+    def _raw_reaction_mocks(self, channel_id, message_id, user_id):
+        """Sets up mocks for tests of the `on_raw_reaction_add` event listener."""
+        channel = helpers.MockTextChannel(id=channel_id)
+        self.bot.get_all_channels.return_value = (channel,)
+
+        message = helpers.MockMessage(id=message_id)
+
+        channel.fetch_message.return_value = message
+
+        member = helpers.MockMember(id=user_id, roles=[self.staff_role])
+        message.guild.members = (member,)
+
+        payload = MagicMock(channel_id=channel_id, message_id=message_id, user_id=user_id)
+
+        return channel, message, member, payload
+
+    @helpers.async_test
+    async def test_on_raw_reaction_add_returns_for_bot_and_non_staff_members(self):
+        """The `on_raw_reaction_add` event handler should return for bot users or non-staff members."""
+        channel_id = 1234
+        message_id = 2345
+        user_id = 3456
+
+        channel, message, _, payload = self._raw_reaction_mocks(channel_id, message_id, user_id)
+
+        test_cases = (
+            ("non-staff member", helpers.MockMember(id=user_id)),
+            ("bot staff member", helpers.MockMember(id=user_id, roles=[self.staff_role], bot=True)),
+        )
+
+        payload.emoji = self.duck_pond_emoji
+
+        for description, member in test_cases:
+            message.guild.members = (member, )
+            with self.subTest(test_case=description), patch(f"{MODULE_PATH}.DuckPond.has_green_checkmark") as checkmark:
+                checkmark.side_effect = AssertionError(
+                    "Expected method to return before calling `self.has_green_checkmark`."
+                )
+                self.assertIsNone(await self.cog.on_raw_reaction_add(payload))
+
+                # Check that we did make it past the payload checks
+                channel.fetch_message.assert_called_once()
+                channel.fetch_message.reset_mock()
+
+    @patch(f"{MODULE_PATH}.DuckPond.is_staff")
+    @patch(f"{MODULE_PATH}.DuckPond.count_ducks", new_callable=helpers.AsyncMock)
+    def test_on_raw_reaction_add_returns_on_message_with_green_checkmark_placed_by_bot(self, count_ducks, is_staff):
+        """The `on_raw_reaction_add` event should return when the message has a green check mark placed by the bot."""
+        channel_id = 31415926535
+        message_id = 27182818284
+        user_id = 16180339887
+
+        channel, message, member, payload = self._raw_reaction_mocks(channel_id, message_id, user_id)
+
+        payload.emoji = helpers.MockPartialEmoji(name=self.unicode_duck_emoji)
+        payload.emoji.is_custom_emoji.return_value = False
+
+        message.reactions = [helpers.MockReaction(emoji=self.checkmark_emoji, users=[self.bot.user])]
+
+        is_staff.return_value = True
+        count_ducks.side_effect = AssertionError("Expected method to return before calling `self.count_ducks`")
+
+        self.assertIsNone(asyncio.run(self.cog.on_raw_reaction_add(payload)))
+
+        # Assert that we've made it past `self.is_staff`
+        is_staff.assert_called_once()
+
+    @helpers.async_test
+    async def test_on_raw_reaction_add_does_not_relay_below_duck_threshold(self):
+        """The `on_raw_reaction_add` listener should not relay messages or attachments below the duck threshold."""
+        test_cases = (
+            (constants.DuckPond.threshold - 1, False),
+            (constants.DuckPond.threshold, True),
+            (constants.DuckPond.threshold + 1, True),
+        )
+
+        channel, message, member, payload = self._raw_reaction_mocks(channel_id=3, message_id=4, user_id=5)
+
+        payload.emoji = self.duck_pond_emoji
+
+        for duck_count, should_relay in test_cases:
+            with patch(f"{MODULE_PATH}.DuckPond.relay_message", new_callable=helpers.AsyncMock) as relay_message:
+                with patch(f"{MODULE_PATH}.DuckPond.count_ducks", new_callable=helpers.AsyncMock) as count_ducks:
+                    count_ducks.return_value = duck_count
+                    with self.subTest(duck_count=duck_count, should_relay=should_relay):
+                        await self.cog.on_raw_reaction_add(payload)
+
+                        # Confirm that we've made it past counting
+                        count_ducks.assert_called_once()
+
+                        # Did we relay a message?
+                        has_relayed = relay_message.called
+                        self.assertEqual(has_relayed, should_relay)
+
+                        if should_relay:
+                            relay_message.assert_called_once_with(message)
+
+    @helpers.async_test
+    async def test_on_raw_reaction_remove_prevents_removal_of_green_checkmark_depending_on_the_duck_count(self):
+        """The `on_raw_reaction_remove` listener prevents removal of the check mark on messages with enough ducks."""
+        checkmark = helpers.MockPartialEmoji(name=self.checkmark_emoji)
+
+        message = helpers.MockMessage(id=1234)
+
+        channel = helpers.MockTextChannel(id=98765)
+        channel.fetch_message.return_value = message
+
+        self.bot.get_all_channels.return_value = (channel, )
+
+        payload = MagicMock(channel_id=channel.id, message_id=message.id, emoji=checkmark)
+
+        test_cases = (
+            (constants.DuckPond.threshold - 1, False),
+            (constants.DuckPond.threshold, True),
+            (constants.DuckPond.threshold + 1, True),
+        )
+        for duck_count, should_re_add_checkmark in test_cases:
+            with patch(f"{MODULE_PATH}.DuckPond.count_ducks", new_callable=helpers.AsyncMock) as count_ducks:
+                count_ducks.return_value = duck_count
+                with self.subTest(duck_count=duck_count, should_re_add_checkmark=should_re_add_checkmark):
+                    await self.cog.on_raw_reaction_remove(payload)
+
+                    # Check if we fetched the message
+                    channel.fetch_message.assert_called_once_with(message.id)
+
+                    # Check if we actually counted the number of ducks
+                    count_ducks.assert_called_once_with(message)
+
+                    has_re_added_checkmark = message.add_reaction.called
+                    self.assertEqual(should_re_add_checkmark, has_re_added_checkmark)
+
+                    if should_re_add_checkmark:
+                        message.add_reaction.assert_called_once_with(self.checkmark_emoji)
+                        message.add_reaction.reset_mock()
+
+                    # reset mocks
+                    channel.fetch_message.reset_mock()
+                    message.reset_mock()
+
+    def test_on_raw_reaction_remove_ignores_removal_of_non_checkmark_reactions(self):
+        """The `on_raw_reaction_remove` listener should ignore the removal of non-check mark emojis."""
+        channel = helpers.MockTextChannel(id=98765)
+
+        channel.fetch_message.side_effect = AssertionError(
+            "Expected method to return before calling `channel.fetch_message`"
+        )
+
+        self.bot.get_all_channels.return_value = (channel, )
+
+        payload = MagicMock(emoji=helpers.MockPartialEmoji(name=self.thumbs_up_emoji), channel_id=channel.id)
+
+        self.assertIsNone(asyncio.run(self.cog.on_raw_reaction_remove(payload)))
+
+        channel.fetch_message.assert_not_called()
+
+
+class DuckPondSetupTests(unittest.TestCase):
+    """Tests setup of the `DuckPond` cog."""
+
+    def test_setup(self):
+        """Setup of the cog should log a message at `INFO` level."""
+        bot = helpers.MockBot()
+        log = logging.getLogger('bot.cogs.duck_pond')
+
+        with self.assertLogs(logger=log, level=logging.INFO) as log_watcher:
+            duck_pond.setup(bot)
+
+        self.assertEqual(len(log_watcher.records), 1)
+        record = log_watcher.records[0]
+        self.assertEqual(record.levelno, logging.INFO)
+
+        bot.add_cog.assert_called_once()
diff --git a/tests/bot/cogs/test_information.py b/tests/bot/cogs/test_information.py
index 9bbd35a91..4496a2ae0 100644
--- a/tests/bot/cogs/test_information.py
+++ b/tests/bot/cogs/test_information.py
@@ -7,7 +7,11 @@ import discord
 
 from bot import constants
 from bot.cogs import information
-from tests.helpers import AsyncMock, MockBot, MockContext, MockGuild, MockMember, MockRole
+from bot.decorators import InChannelCheckFailure
+from tests import helpers
+
+
+COG_PATH = "bot.cogs.information.Information"
 
 
 class InformationCogTests(unittest.TestCase):
@@ -15,22 +19,22 @@ class InformationCogTests(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
-        cls.moderator_role = MockRole(name="Moderator", role_id=constants.Roles.moderator)
+        cls.moderator_role = helpers.MockRole(name="Moderator", id=constants.Roles.moderator)
 
     def setUp(self):
         """Sets up fresh objects for each test."""
-        self.bot = MockBot()
+        self.bot = helpers.MockBot()
 
         self.cog = information.Information(self.bot)
 
-        self.ctx = MockContext()
+        self.ctx = helpers.MockContext()
         self.ctx.author.roles.append(self.moderator_role)
 
     def test_roles_command_command(self):
         """Test if the `role_info` command correctly returns the `moderator_role`."""
         self.ctx.guild.roles.append(self.moderator_role)
 
-        self.cog.roles_info.can_run = AsyncMock()
+        self.cog.roles_info.can_run = helpers.AsyncMock()
         self.cog.roles_info.can_run.return_value = True
 
         coroutine = self.cog.roles_info.callback(self.cog, self.ctx)
@@ -48,18 +52,18 @@ class InformationCogTests(unittest.TestCase):
 
     def test_role_info_command(self):
         """Tests the `role info` command."""
-        dummy_role = MockRole(
+        dummy_role = helpers.MockRole(
             name="Dummy",
-            role_id=112233445566778899,
+            id=112233445566778899,
             colour=discord.Colour.blurple(),
             position=10,
             members=[self.ctx.author],
             permissions=discord.Permissions(0)
         )
 
-        admin_role = MockRole(
+        admin_role = helpers.MockRole(
             name="Admins",
-            role_id=998877665544332211,
+            id=998877665544332211,
             colour=discord.Colour.red(),
             position=3,
             members=[self.ctx.author],
@@ -68,7 +72,7 @@ class InformationCogTests(unittest.TestCase):
 
         self.ctx.guild.roles.append([dummy_role, admin_role])
 
-        self.cog.role_info.can_run = AsyncMock()
+        self.cog.role_info.can_run = helpers.AsyncMock()
         self.cog.role_info.can_run.return_value = True
 
         coroutine = self.cog.role_info.callback(self.cog, self.ctx, dummy_role, admin_role)
@@ -99,7 +103,7 @@ class InformationCogTests(unittest.TestCase):
     def test_server_info_command(self, time_since_patch):
         time_since_patch.return_value = '2 days ago'
 
-        self.ctx.guild = MockGuild(
+        self.ctx.guild = helpers.MockGuild(
             features=('lemons', 'apples'),
             region="The Moon",
             roles=[self.moderator_role],
@@ -121,10 +125,10 @@ class InformationCogTests(unittest.TestCase):
                 )
             ],
             members=[
-                *(MockMember(status='online') for _ in range(2)),
-                *(MockMember(status='idle') for _ in range(1)),
-                *(MockMember(status='dnd') for _ in range(4)),
-                *(MockMember(status='offline') for _ in range(3)),
+                *(helpers.MockMember(status='online') for _ in range(2)),
+                *(helpers.MockMember(status='idle') for _ in range(1)),
+                *(helpers.MockMember(status='dnd') for _ in range(4)),
+                *(helpers.MockMember(status='offline') for _ in range(3)),
             ],
             member_count=1_234,
             icon_url='a-lemon.jpg',
@@ -162,3 +166,417 @@ class InformationCogTests(unittest.TestCase):
             )
         )
         self.assertEqual(embed.thumbnail.url, 'a-lemon.jpg')
+
+
+class UserInfractionHelperMethodTests(unittest.TestCase):
+    """Tests for the helper methods of the `!user` command."""
+
+    def setUp(self):
+        """Common set-up steps done before for each test."""
+        self.bot = helpers.MockBot()
+        self.bot.api_client.get = helpers.AsyncMock()
+        self.cog = information.Information(self.bot)
+        self.member = helpers.MockMember(id=1234)
+
+    def test_user_command_helper_method_get_requests(self):
+        """The helper methods should form the correct get requests."""
+        test_values = (
+            {
+                "helper_method": self.cog.basic_user_infraction_counts,
+                "expected_args": ("bot/infractions", {'hidden': 'False', 'user__id': str(self.member.id)}),
+            },
+            {
+                "helper_method": self.cog.expanded_user_infraction_counts,
+                "expected_args": ("bot/infractions", {'user__id': str(self.member.id)}),
+            },
+            {
+                "helper_method": self.cog.user_nomination_counts,
+                "expected_args": ("bot/nominations", {'user__id': str(self.member.id)}),
+            },
+        )
+
+        for test_value in test_values:
+            helper_method = test_value["helper_method"]
+            endpoint, params = test_value["expected_args"]
+
+            with self.subTest(method=helper_method, endpoint=endpoint, params=params):
+                asyncio.run(helper_method(self.member))
+                self.bot.api_client.get.assert_called_once_with(endpoint, params=params)
+                self.bot.api_client.get.reset_mock()
+
+    def _method_subtests(self, method, test_values, default_header):
+        """Helper method that runs the subtests for the different helper methods."""
+        for test_value in test_values:
+            api_response = test_value["api response"]
+            expected_lines = test_value["expected_lines"]
+
+            with self.subTest(method=method, api_response=api_response, expected_lines=expected_lines):
+                self.bot.api_client.get.return_value = api_response
+
+                expected_output = "\n".join(default_header + expected_lines)
+                actual_output = asyncio.run(method(self.member))
+
+                self.assertEqual(expected_output, actual_output)
+
+    def test_basic_user_infraction_counts_returns_correct_strings(self):
+        """The method should correctly list both the total and active number of non-hidden infractions."""
+        test_values = (
+            # No infractions means zero counts
+            {
+                "api response": [],
+                "expected_lines": ["Total: 0", "Active: 0"],
+            },
+            # Simple, single-infraction dictionaries
+            {
+                "api response": [{"type": "ban", "active": True}],
+                "expected_lines": ["Total: 1", "Active: 1"],
+            },
+            {
+                "api response": [{"type": "ban", "active": False}],
+                "expected_lines": ["Total: 1", "Active: 0"],
+            },
+            # Multiple infractions with various `active` status
+            {
+                "api response": [
+                    {"type": "ban", "active": True},
+                    {"type": "kick", "active": False},
+                    {"type": "ban", "active": True},
+                    {"type": "ban", "active": False},
+                ],
+                "expected_lines": ["Total: 4", "Active: 2"],
+            },
+        )
+
+        header = ["**Infractions**"]
+
+        self._method_subtests(self.cog.basic_user_infraction_counts, test_values, header)
+
+    def test_expanded_user_infraction_counts_returns_correct_strings(self):
+        """The method should correctly list the total and active number of all infractions split by infraction type."""
+        test_values = (
+            {
+                "api response": [],
+                "expected_lines": ["This user has never received an infraction."],
+            },
+            # Shows non-hidden inactive infraction as expected
+            {
+                "api response": [{"type": "kick", "active": False, "hidden": False}],
+                "expected_lines": ["Kicks: 1"],
+            },
+            # Shows non-hidden active infraction as expected
+            {
+                "api response": [{"type": "mute", "active": True, "hidden": False}],
+                "expected_lines": ["Mutes: 1 (1 active)"],
+            },
+            # Shows hidden inactive infraction as expected
+            {
+                "api response": [{"type": "superstar", "active": False, "hidden": True}],
+                "expected_lines": ["Superstars: 1"],
+            },
+            # Shows hidden active infraction as expected
+            {
+                "api response": [{"type": "ban", "active": True, "hidden": True}],
+                "expected_lines": ["Bans: 1 (1 active)"],
+            },
+            # Correctly displays tally of multiple infractions of mixed properties in alphabetical order
+            {
+                "api response": [
+                    {"type": "kick", "active": False, "hidden": True},
+                    {"type": "ban", "active": True, "hidden": True},
+                    {"type": "superstar", "active": True, "hidden": True},
+                    {"type": "mute", "active": True, "hidden": True},
+                    {"type": "ban", "active": False, "hidden": False},
+                    {"type": "note", "active": False, "hidden": True},
+                    {"type": "note", "active": False, "hidden": True},
+                    {"type": "warn", "active": False, "hidden": False},
+                    {"type": "note", "active": False, "hidden": True},
+                ],
+                "expected_lines": [
+                    "Bans: 2 (1 active)",
+                    "Kicks: 1",
+                    "Mutes: 1 (1 active)",
+                    "Notes: 3",
+                    "Superstars: 1 (1 active)",
+                    "Warns: 1",
+                ],
+            },
+        )
+
+        header = ["**Infractions**"]
+
+        self._method_subtests(self.cog.expanded_user_infraction_counts, test_values, header)
+
+    def test_user_nomination_counts_returns_correct_strings(self):
+        """The method should list the number of active and historical nominations for the user."""
+        test_values = (
+            {
+                "api response": [],
+                "expected_lines": ["This user has never been nominated."],
+            },
+            {
+                "api response": [{'active': True}],
+                "expected_lines": ["This user is **currently** nominated (1 nomination in total)."],
+            },
+            {
+                "api response": [{'active': True}, {'active': False}],
+                "expected_lines": ["This user is **currently** nominated (2 nominations in total)."],
+            },
+            {
+                "api response": [{'active': False}],
+                "expected_lines": ["This user has 1 historical nomination, but is currently not nominated."],
+            },
+            {
+                "api response": [{'active': False}, {'active': False}],
+                "expected_lines": ["This user has 2 historical nominations, but is currently not nominated."],
+            },
+
+        )
+
+        header = ["**Nominations**"]
+
+        self._method_subtests(self.cog.user_nomination_counts, test_values, header)
+
+
[email protected]("bot.cogs.information.time_since", new=unittest.mock.MagicMock(return_value="1 year ago"))
[email protected]("bot.cogs.information.constants.MODERATION_CHANNELS", new=[50])
+class UserEmbedTests(unittest.TestCase):
+    """Tests for the creation of the `!user` embed."""
+
+    def setUp(self):
+        """Common set-up steps done before for each test."""
+        self.bot = helpers.MockBot()
+        self.bot.api_client.get = helpers.AsyncMock()
+        self.cog = information.Information(self.bot)
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_uses_string_representation_of_user_in_title_if_nick_is_not_available(self):
+        """The embed should use the string representation of the user if they don't have a nick."""
+        ctx = helpers.MockContext(channel=helpers.MockTextChannel(id=1))
+        user = helpers.MockMember()
+        user.nick = None
+        user.__str__ = unittest.mock.Mock(return_value="Mr. Hemlock")
+
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        self.assertEqual(embed.title, "Mr. Hemlock")
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_uses_nick_in_title_if_available(self):
+        """The embed should use the nick if it's available."""
+        ctx = helpers.MockContext(channel=helpers.MockTextChannel(id=1))
+        user = helpers.MockMember()
+        user.nick = "Cat lover"
+        user.__str__ = unittest.mock.Mock(return_value="Mr. Hemlock")
+
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        self.assertEqual(embed.title, "Cat lover (Mr. Hemlock)")
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_ignores_everyone_role(self):
+        """Created `!user` embeds should not contain mention of the @everyone-role."""
+        ctx = helpers.MockContext(channel=helpers.MockTextChannel(id=1))
+        admins_role = helpers.MockRole(name='Admins')
+        admins_role.colour = 100
+
+        # A `MockMember` has the @Everyone role by default; we add the Admins to that.
+        user = helpers.MockMember(roles=[admins_role], top_role=admins_role)
+
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        self.assertIn("&Admins", embed.description)
+        self.assertNotIn("&Everyone", embed.description)
+
+    @unittest.mock.patch(f"{COG_PATH}.expanded_user_infraction_counts", new_callable=helpers.AsyncMock)
+    @unittest.mock.patch(f"{COG_PATH}.user_nomination_counts", new_callable=helpers.AsyncMock)
+    def test_create_user_embed_expanded_information_in_moderation_channels(self, nomination_counts, infraction_counts):
+        """The embed should contain expanded infractions and nomination info in mod channels."""
+        ctx = helpers.MockContext(channel=helpers.MockTextChannel(id=50))
+
+        moderators_role = helpers.MockRole(name='Moderators')
+        moderators_role.colour = 100
+
+        infraction_counts.return_value = "expanded infractions info"
+        nomination_counts.return_value = "nomination info"
+
+        user = helpers.MockMember(id=314, roles=[moderators_role], top_role=moderators_role)
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        infraction_counts.assert_called_once_with(user)
+        nomination_counts.assert_called_once_with(user)
+
+        self.assertEqual(
+            textwrap.dedent(f"""
+                **User Information**
+                Created: {"1 year ago"}
+                Profile: {user.mention}
+                ID: {user.id}
+
+                **Member Information**
+                Joined: {"1 year ago"}
+                Roles: &Moderators
+
+                expanded infractions info
+
+                nomination info
+            """).strip(),
+            embed.description
+        )
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new_callable=helpers.AsyncMock)
+    def test_create_user_embed_basic_information_outside_of_moderation_channels(self, infraction_counts):
+        """The embed should contain only basic infraction data outside of mod channels."""
+        ctx = helpers.MockContext(channel=helpers.MockTextChannel(id=100))
+
+        moderators_role = helpers.MockRole(name='Moderators')
+        moderators_role.colour = 100
+
+        infraction_counts.return_value = "basic infractions info"
+
+        user = helpers.MockMember(id=314, roles=[moderators_role], top_role=moderators_role)
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        infraction_counts.assert_called_once_with(user)
+
+        self.assertEqual(
+            textwrap.dedent(f"""
+                **User Information**
+                Created: {"1 year ago"}
+                Profile: {user.mention}
+                ID: {user.id}
+
+                **Member Information**
+                Joined: {"1 year ago"}
+                Roles: &Moderators
+
+                basic infractions info
+            """).strip(),
+            embed.description
+        )
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_uses_top_role_colour_when_user_has_roles(self):
+        """The embed should be created with the colour of the top role, if a top role is available."""
+        ctx = helpers.MockContext()
+
+        moderators_role = helpers.MockRole(name='Moderators')
+        moderators_role.colour = 100
+
+        user = helpers.MockMember(id=314, roles=[moderators_role], top_role=moderators_role)
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        self.assertEqual(embed.colour, discord.Colour(moderators_role.colour))
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_uses_blurple_colour_when_user_has_no_roles(self):
+        """The embed should be created with a blurple colour if the user has no assigned roles."""
+        ctx = helpers.MockContext()
+
+        user = helpers.MockMember(id=217)
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        self.assertEqual(embed.colour, discord.Colour.blurple())
+
+    @unittest.mock.patch(f"{COG_PATH}.basic_user_infraction_counts", new=helpers.AsyncMock(return_value=""))
+    def test_create_user_embed_uses_png_format_of_user_avatar_as_thumbnail(self):
+        """The embed thumbnail should be set to the user's avatar in `png` format."""
+        ctx = helpers.MockContext()
+
+        user = helpers.MockMember(id=217)
+        user.avatar_url_as.return_value = "avatar url"
+        embed = asyncio.run(self.cog.create_user_embed(ctx, user))
+
+        user.avatar_url_as.assert_called_once_with(format="png")
+        self.assertEqual(embed.thumbnail.url, "avatar url")
+
+
[email protected]("bot.cogs.information.constants")
+class UserCommandTests(unittest.TestCase):
+    """Tests for the `!user` command."""
+
+    def setUp(self):
+        """Set up steps executed before each test is run."""
+        self.bot = helpers.MockBot()
+        self.cog = information.Information(self.bot)
+
+        self.moderator_role = helpers.MockRole(name="Moderators", id=2, position=10)
+        self.flautist_role = helpers.MockRole(name="Flautists", id=3, position=2)
+        self.bassist_role = helpers.MockRole(name="Bassists", id=4, position=3)
+
+        self.author = helpers.MockMember(id=1, name="syntaxaire")
+        self.moderator = helpers.MockMember(id=2, name="riffautae", roles=[self.moderator_role])
+        self.target = helpers.MockMember(id=3, name="__fluzz__")
+
+    def test_regular_member_cannot_target_another_member(self, constants):
+        """A regular user should not be able to use `!user` targeting another user."""
+        constants.MODERATION_ROLES = [self.moderator_role.id]
+
+        ctx = helpers.MockContext(author=self.author)
+
+        asyncio.run(self.cog.user_info.callback(self.cog, ctx, self.target))
+
+        ctx.send.assert_called_once_with("You may not use this command on users other than yourself.")
+
+    def test_regular_member_cannot_use_command_outside_of_bot_commands(self, constants):
+        """A regular user should not be able to use this command outside of bot-commands."""
+        constants.MODERATION_ROLES = [self.moderator_role.id]
+        constants.STAFF_ROLES = [self.moderator_role.id]
+        constants.Channels.bot = 50
+
+        ctx = helpers.MockContext(author=self.author, channel=helpers.MockTextChannel(id=100))
+
+        msg = "Sorry, but you may only use this command within <#50>."
+        with self.assertRaises(InChannelCheckFailure, msg=msg):
+            asyncio.run(self.cog.user_info.callback(self.cog, ctx))
+
+    @unittest.mock.patch("bot.cogs.information.Information.create_user_embed", new_callable=helpers.AsyncMock)
+    def test_regular_user_may_use_command_in_bot_commands_channel(self, create_embed, constants):
+        """A regular user should be allowed to use `!user` targeting themselves in bot-commands."""
+        constants.STAFF_ROLES = [self.moderator_role.id]
+        constants.Channels.bot = 50
+
+        ctx = helpers.MockContext(author=self.author, channel=helpers.MockTextChannel(id=50))
+
+        asyncio.run(self.cog.user_info.callback(self.cog, ctx))
+
+        create_embed.assert_called_once_with(ctx, self.author)
+        ctx.send.assert_called_once()
+
+    @unittest.mock.patch("bot.cogs.information.Information.create_user_embed", new_callable=helpers.AsyncMock)
+    def test_regular_user_can_explicitly_target_themselves(self, create_embed, constants):
+        """A user should target itself with `!user` when a `user` argument was not provided."""
+        constants.STAFF_ROLES = [self.moderator_role.id]
+        constants.Channels.bot = 50
+
+        ctx = helpers.MockContext(author=self.author, channel=helpers.MockTextChannel(id=50))
+
+        asyncio.run(self.cog.user_info.callback(self.cog, ctx, self.author))
+
+        create_embed.assert_called_once_with(ctx, self.author)
+        ctx.send.assert_called_once()
+
+    @unittest.mock.patch("bot.cogs.information.Information.create_user_embed", new_callable=helpers.AsyncMock)
+    def test_staff_members_can_bypass_channel_restriction(self, create_embed, constants):
+        """Staff members should be able to bypass the bot-commands channel restriction."""
+        constants.STAFF_ROLES = [self.moderator_role.id]
+        constants.Channels.bot = 50
+
+        ctx = helpers.MockContext(author=self.moderator, channel=helpers.MockTextChannel(id=200))
+
+        asyncio.run(self.cog.user_info.callback(self.cog, ctx))
+
+        create_embed.assert_called_once_with(ctx, self.moderator)
+        ctx.send.assert_called_once()
+
+    @unittest.mock.patch("bot.cogs.information.Information.create_user_embed", new_callable=helpers.AsyncMock)
+    def test_moderators_can_target_another_member(self, create_embed, constants):
+        """A moderator should be able to use `!user` targeting another user."""
+        constants.MODERATION_ROLES = [self.moderator_role.id]
+        constants.STAFF_ROLES = [self.moderator_role.id]
+
+        ctx = helpers.MockContext(author=self.moderator, channel=helpers.MockTextChannel(id=50))
+
+        asyncio.run(self.cog.user_info.callback(self.cog, ctx, self.target))
+
+        create_embed.assert_called_once_with(ctx, self.target)
+        ctx.send.assert_called_once()
diff --git a/tests/bot/cogs/test_token_remover.py b/tests/bot/cogs/test_token_remover.py
index dfb1bafc9..3276cf5a5 100644
--- a/tests/bot/cogs/test_token_remover.py
+++ b/tests/bot/cogs/test_token_remover.py
@@ -24,7 +24,7 @@ class TokenRemoverTests(unittest.TestCase):
         self.bot.get_cog.return_value.send_log_message = AsyncMock()
         self.cog = TokenRemover(bot=self.bot)
 
-        self.msg = MockMessage(message_id=555, content='')
+        self.msg = MockMessage(id=555, content='')
         self.msg.author.__str__ = MagicMock()
         self.msg.author.__str__.return_value = 'lemon'
         self.msg.author.bot = False
diff --git a/tests/bot/rules/test_links.py b/tests/bot/rules/test_links.py
new file mode 100644
index 000000000..be832843b
--- /dev/null
+++ b/tests/bot/rules/test_links.py
@@ -0,0 +1,101 @@
+import unittest
+from typing import List, NamedTuple, Tuple
+
+from bot.rules import links
+from tests.helpers import async_test
+
+
+class FakeMessage(NamedTuple):
+    author: str
+    content: str
+
+
+class Case(NamedTuple):
+    recent_messages: List[FakeMessage]
+    relevant_messages: Tuple[FakeMessage]
+    culprit: Tuple[str]
+    total_links: int
+
+
+def msg(author: str, total_links: int) -> FakeMessage:
+    """Makes a message with *total_links* links."""
+    content = " ".join(["https://pydis.com"] * total_links)
+    return FakeMessage(author=author, content=content)
+
+
+class LinksTests(unittest.TestCase):
+    """Tests applying the `links` rule."""
+
+    def setUp(self):
+        self.config = {
+            "max": 2,
+            "interval": 10
+        }
+
+    @async_test
+    async def test_links_within_limit(self):
+        """Messages with an allowed amount of links."""
+        cases = (
+            [msg("bob", 0)],
+            [msg("bob", 2)],
+            [msg("bob", 3)],  # Filter only applies if len(messages_with_links) > 1
+            [msg("bob", 1), msg("bob", 1)],
+            [msg("bob", 2), msg("alice", 2)]  # Only messages from latest author count
+        )
+
+        for recent_messages in cases:
+            last_message = recent_messages[0]
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                config=self.config
+            ):
+                self.assertIsNone(
+                    await links.apply(last_message, recent_messages, self.config)
+                )
+
+    @async_test
+    async def test_links_exceeding_limit(self):
+        """Messages with a a higher than allowed amount of links."""
+        cases = (
+            Case(
+                [msg("bob", 1), msg("bob", 2)],
+                (msg("bob", 1), msg("bob", 2)),
+                ("bob",),
+                3
+            ),
+            Case(
+                [msg("alice", 1), msg("alice", 1), msg("alice", 1)],
+                (msg("alice", 1), msg("alice", 1), msg("alice", 1)),
+                ("alice",),
+                3
+            ),
+            Case(
+                [msg("alice", 2), msg("bob", 3), msg("alice", 1)],
+                (msg("alice", 2), msg("alice", 1)),
+                ("alice",),
+                3
+            )
+        )
+
+        for recent_messages, relevant_messages, culprit, total_links in cases:
+            last_message = recent_messages[0]
+
+            with self.subTest(
+                last_message=last_message,
+                recent_messages=recent_messages,
+                relevant_messages=relevant_messages,
+                culprit=culprit,
+                total_links=total_links,
+                config=self.config
+            ):
+                desired_output = (
+                    f"sent {total_links} links in {self.config['interval']}s",
+                    culprit,
+                    relevant_messages
+                )
+                self.assertTupleEqual(
+                    await links.apply(last_message, recent_messages, self.config),
+                    desired_output
+                )
diff --git a/tests/bot/test_api.py b/tests/bot/test_api.py
index e0ede0eb1..5a88adc5c 100644
--- a/tests/bot/test_api.py
+++ b/tests/bot/test_api.py
@@ -121,7 +121,9 @@ class LoggingHandlerTests(LoggingTestCase):
 
     def test_schedule_queued_tasks_for_nonempty_queue(self):
         """`APILoggingHandler` should schedule logs when the queue is not empty."""
-        with self.assertLogs(level=logging.DEBUG) as logs, patch('asyncio.create_task') as create_task:
+        log = logging.getLogger("bot.api")
+
+        with self.assertLogs(logger=log, level=logging.DEBUG) as logs, patch('asyncio.create_task') as create_task:
             self.log_handler.queue = [555]
             self.log_handler.schedule_queued_tasks()
             self.assertListEqual(self.log_handler.queue, [])
diff --git a/tests/bot/test_utils.py b/tests/bot/test_utils.py
new file mode 100644
index 000000000..58ae2a81a
--- /dev/null
+++ b/tests/bot/test_utils.py
@@ -0,0 +1,52 @@
+import unittest
+
+from bot import utils
+
+
+class CaseInsensitiveDictTests(unittest.TestCase):
+    """Tests for the `CaseInsensitiveDict` container."""
+
+    def test_case_insensitive_key_access(self):
+        """Tests case insensitive key access and storage."""
+        instance = utils.CaseInsensitiveDict()
+
+        key = 'LEMON'
+        value = 'trees'
+
+        instance[key] = value
+        self.assertIn(key, instance)
+        self.assertEqual(instance.get(key), value)
+        self.assertEqual(instance.get(key.casefold()), value)
+        self.assertEqual(instance.pop(key.casefold()), value)
+        self.assertNotIn(key, instance)
+        self.assertNotIn(key.casefold(), instance)
+
+        instance.setdefault(key, value)
+        del instance[key]
+        self.assertNotIn(key, instance)
+
+    def test_initialization_from_kwargs(self):
+        """Tests creating the dictionary from keyword arguments."""
+        instance = utils.CaseInsensitiveDict({'FOO': 'bar'})
+        self.assertEqual(instance['foo'], 'bar')
+
+    def test_update_from_other_mapping(self):
+        """Tests updating the dictionary from another mapping."""
+        instance = utils.CaseInsensitiveDict()
+        instance.update({'FOO': 'bar'})
+        self.assertEqual(instance['foo'], 'bar')
+
+
+class ChunkTests(unittest.TestCase):
+    """Tests the `chunk` method."""
+
+    def test_empty_chunking(self):
+        """Tests chunking on an empty iterable."""
+        generator = utils.chunks(iterable=[], size=5)
+        self.assertEqual(list(generator), [])
+
+    def test_list_chunking(self):
+        """Tests chunking a non-empty list."""
+        iterable = [1, 2, 3, 4, 5]
+        generator = utils.chunks(iterable=iterable, size=2)
+        self.assertEqual(list(generator), [[1, 2], [3, 4], [5]])
diff --git a/tests/bot/utils/test_checks.py b/tests/bot/utils/test_checks.py
index 19b758336..9610771e5 100644
--- a/tests/bot/utils/test_checks.py
+++ b/tests/bot/utils/test_checks.py
@@ -22,7 +22,7 @@ class ChecksTests(unittest.TestCase):
 
     def test_with_role_check_with_guild_and_required_role(self):
         """`with_role_check` returns `True` if `Context.author` has the required role."""
-        self.ctx.author.roles.append(MockRole(role_id=10))
+        self.ctx.author.roles.append(MockRole(id=10))
         self.assertTrue(checks.with_role_check(self.ctx, 10))
 
     def test_without_role_check_without_guild(self):
@@ -33,13 +33,13 @@ class ChecksTests(unittest.TestCase):
     def test_without_role_check_returns_false_with_unwanted_role(self):
         """`without_role_check` returns `False` if `Context.author` has unwanted role."""
         role_id = 42
-        self.ctx.author.roles.append(MockRole(role_id=role_id))
+        self.ctx.author.roles.append(MockRole(id=role_id))
         self.assertFalse(checks.without_role_check(self.ctx, role_id))
 
     def test_without_role_check_returns_true_without_unwanted_role(self):
         """`without_role_check` returns `True` if `Context.author` does not have unwanted role."""
         role_id = 42
-        self.ctx.author.roles.append(MockRole(role_id=role_id))
+        self.ctx.author.roles.append(MockRole(id=role_id))
         self.assertTrue(checks.without_role_check(self.ctx, role_id + 10))
 
     def test_in_channel_check_for_correct_channel(self):