diff --git a/alembic/versions/b2d511552a1f_add_custom_commands.py b/alembic/versions/b2d511552a1f_add_custom_commands.py
new file mode 100644
index 0000000..83b004a
--- /dev/null
+++ b/alembic/versions/b2d511552a1f_add_custom_commands.py
@@ -0,0 +1,57 @@
+"""Add custom commands
+
+Revision ID: b2d511552a1f
+Revises: 4ec79dd5b191
+Create Date: 2022-06-21 22:10:05.590846
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'b2d511552a1f'
+down_revision = '4ec79dd5b191'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('custom_commands',
+    sa.Column('command_id', sa.Integer(), nullable=False),
+    sa.Column('name', sa.Text(), nullable=False),
+    sa.Column('indexed_name', sa.Text(), nullable=False),
+    sa.Column('response', sa.Text(), nullable=False),
+    sa.PrimaryKeyConstraint('command_id'),
+    sa.UniqueConstraint('name')
+    )
+    with op.batch_alter_table('custom_commands', schema=None) as batch_op:
+        batch_op.create_index(batch_op.f('ix_custom_commands_indexed_name'), ['indexed_name'], unique=False)
+
+    op.create_table('custom_command_aliases',
+    sa.Column('alias_id', sa.Integer(), nullable=False),
+    sa.Column('alias', sa.Text(), nullable=False),
+    sa.Column('indexed_alias', sa.Text(), nullable=False),
+    sa.Column('command_id', sa.Integer(), nullable=True),
+    sa.ForeignKeyConstraint(['command_id'], ['custom_commands.command_id'], ),
+    sa.PrimaryKeyConstraint('alias_id'),
+    sa.UniqueConstraint('alias')
+    )
+    with op.batch_alter_table('custom_command_aliases', schema=None) as batch_op:
+        batch_op.create_index(batch_op.f('ix_custom_command_aliases_indexed_alias'), ['indexed_alias'], unique=False)
+
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('custom_command_aliases', schema=None) as batch_op:
+        batch_op.drop_index(batch_op.f('ix_custom_command_aliases_indexed_alias'))
+
+    op.drop_table('custom_command_aliases')
+    with op.batch_alter_table('custom_commands', schema=None) as batch_op:
+        batch_op.drop_index(batch_op.f('ix_custom_commands_indexed_name'))
+
+    op.drop_table('custom_commands')
+    # ### end Alembic commands ###
diff --git a/database/crud/custom_commands.py b/database/crud/custom_commands.py
new file mode 100644
index 0000000..afd41ce
--- /dev/null
+++ b/database/crud/custom_commands.py
@@ -0,0 +1,68 @@
+from typing import Optional
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from database.exceptions.constraints import DuplicateInsertException
+from database.exceptions.not_found import NoResultFoundException
+from database.models import CustomCommand, CustomCommandAlias
+
+
+def clean_name(name: str) -> str:
+    """Convert a name to lowercase & remove spaces to allow easier matching"""
+    return name.lower().replace(" ", "")
+
+
+async def create_command(session: AsyncSession, name: str, response: str) -> CustomCommand:
+    """Create a new custom command"""
+    # Check if command or alias already exists
+    command = await get_command(session, name)
+    if command is not None:
+        raise DuplicateInsertException
+
+    command = CustomCommand(name=name, indexed_name=clean_name(name), response=response)
+    session.add(command)
+    await session.commit()
+    return command
+
+
+async def create_alias(session: AsyncSession, command: str, alias: str) -> CustomCommandAlias:
+    """Create an alias for a command"""
+    # Check if the command exists
+    command_instance = await get_command(session, command)
+    if command_instance is None:
+        raise NoResultFoundException
+
+    # Check if the alias exists (either as an alias or as a name)
+    alias_instance = await get_command(session, alias)
+    if alias_instance is not None:
+        raise DuplicateInsertException
+
+    alias_instance = CustomCommandAlias(alias=alias, indexed_alias=clean_name(alias), command=command_instance)
+    session.add(alias_instance)
+    await session.commit()
+
+    return alias_instance
+
+
+async def get_command(session: AsyncSession, message: str) -> Optional[CustomCommand]:
+    """Try to get a command out of a message"""
+    # Search lowercase & without spaces, and strip the prefix
+    message = clean_name(message)
+    return (await get_command_by_name(session, message)) or (await get_command_by_alias(session, message))
+
+
+async def get_command_by_name(session: AsyncSession, message: str) -> Optional[CustomCommand]:
+    """Try to get a command by its name"""
+    statement = select(CustomCommand).where(CustomCommand.indexed_name == message)
+    return (await session.execute(statement)).scalar_one_or_none()
+
+
+async def get_command_by_alias(session: AsyncSession, message: str) -> Optional[CustomCommand]:
+    """Try to get a command by its alias"""
+    statement = select(CustomCommandAlias).where(CustomCommandAlias.indexed_alias == message)
+    alias = (await session.execute(statement)).scalar_one_or_none()
+    if alias is None:
+        return None
+
+    return alias.command
diff --git a/database/crud/ufora_announcements.py b/database/crud/ufora_announcements.py
index 0d8e15f..c4d67f6 100644
--- a/database/crud/ufora_announcements.py
+++ b/database/crud/ufora_announcements.py
@@ -13,7 +13,7 @@ async def get_courses_with_announcements(session: AsyncSession) -> list[UforaCou
 
 
 async def create_new_announcement(
-    session: AsyncSession, announcement_id: int, course: UforaCourse, publication_date: datetime
+    session: AsyncSession, announcement_id: int, course: UforaCourse, publication_date: datetime.datetime
 ) -> UforaAnnouncement:
     """Add a new announcement to the database"""
     new_announcement = UforaAnnouncement(
diff --git a/database/exceptions/__init__.py b/database/exceptions/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/database/exceptions/constraints.py b/database/exceptions/constraints.py
new file mode 100644
index 0000000..1e78089
--- /dev/null
+++ b/database/exceptions/constraints.py
@@ -0,0 +1,2 @@
+class DuplicateInsertException(Exception):
+    """Exception raised when a value already exists"""
diff --git a/database/exceptions/not_found.py b/database/exceptions/not_found.py
new file mode 100644
index 0000000..eccfaa5
--- /dev/null
+++ b/database/exceptions/not_found.py
@@ -0,0 +1,2 @@
+class NoResultFoundException(Exception):
+    """Exception raised when nothing was found"""
diff --git a/database/models.py b/database/models.py
index 4414326..1c28d37 100644
--- a/database/models.py
+++ b/database/models.py
@@ -8,6 +8,34 @@ from sqlalchemy.orm import declarative_base, relationship
 Base = declarative_base()
 
 
+class CustomCommand(Base):
+    """Custom commands to fill the hole Dyno couldn't"""
+
+    __tablename__ = "custom_commands"
+
+    command_id: int = Column(Integer, primary_key=True)
+    name: str = Column(Text, nullable=False, unique=True)
+    indexed_name: str = Column(Text, nullable=False, index=True)
+    response: str = Column(Text, nullable=False)
+
+    aliases: list[CustomCommandAlias] = relationship(
+        "CustomCommandAlias", back_populates="command", uselist=True, cascade="all, delete-orphan", lazy="selectin"
+    )
+
+
+class CustomCommandAlias(Base):
+    """Aliases for custom commands"""
+
+    __tablename__ = "custom_command_aliases"
+
+    alias_id: int = Column(Integer, primary_key=True)
+    alias: str = Column(Text, nullable=False, unique=True)
+    indexed_alias: str = Column(Text, nullable=False, index=True)
+    command_id: int = Column(Integer, ForeignKey("custom_commands.command_id"))
+
+    command: CustomCommand = relationship("CustomCommand", back_populates="aliases", uselist=False, lazy="selectin")
+
+
 class UforaCourse(Base):
     """A course on Ufora"""
 
diff --git a/didier/cogs/owner.py b/didier/cogs/owner.py
new file mode 100644
index 0000000..af50633
--- /dev/null
+++ b/didier/cogs/owner.py
@@ -0,0 +1,27 @@
+from typing import Optional
+
+import discord
+from discord.ext import commands
+
+from didier import Didier
+
+
+class Owner(commands.Cog):
+    """Cog for owner-only commands"""
+
+    client: Didier
+
+    def __init__(self, client: Didier):
+        self.client = client
+
+    @commands.command(name="Sync")
+    @commands.is_owner()
+    async def sync(self, ctx: commands.Context, guild: Optional[discord.Guild] = None):
+        """Sync all application-commands in Discord"""
+        await self.client.tree.sync(guild=guild)
+        await ctx.message.add_reaction("🔄")
+
+
+async def setup(client: Didier):
+    """Load the cog"""
+    await client.add_cog(Owner(client))
diff --git a/didier/cogs/tasks.py b/didier/cogs/tasks.py
index b56e426..c37b8b8 100644
--- a/didier/cogs/tasks.py
+++ b/didier/cogs/tasks.py
@@ -1,6 +1,6 @@
 import traceback
 
-from discord.ext import commands, tasks
+from discord.ext import commands, tasks  # type: ignore # Strange & incorrect Mypy error
 
 import settings
 from database.crud.ufora_announcements import remove_old_announcements
@@ -13,7 +13,8 @@ class Tasks(commands.Cog):
 
     client: Didier
 
-    def __init__(self, client: Didier):  # pylint: disable=no-member
+    def __init__(self, client: Didier):
+        # pylint: disable=no-member
         self.client = client
 
         # Only pull announcements if a token was provided
@@ -28,11 +29,12 @@ class Tasks(commands.Cog):
         if settings.UFORA_RSS_TOKEN is None or settings.UFORA_ANNOUNCEMENTS_CHANNEL is None:
             return
 
-        announcements_channel = self.client.get_channel(settings.UFORA_ANNOUNCEMENTS_CHANNEL)
-        announcements = await fetch_ufora_announcements(self.client.db_session)
+        async with self.client.db_session as session:
+            announcements_channel = self.client.get_channel(settings.UFORA_ANNOUNCEMENTS_CHANNEL)
+            announcements = await fetch_ufora_announcements(session)
 
-        for announcement in announcements:
-            await announcements_channel.send(embed=announcement.to_embed())
+            for announcement in announcements:
+                await announcements_channel.send(embed=announcement.to_embed())
 
     @pull_ufora_announcements.before_loop
     async def _before_ufora_announcements(self):
@@ -47,7 +49,8 @@ class Tasks(commands.Cog):
     @tasks.loop(hours=24)
     async def remove_old_ufora_announcements(self):
         """Remove all announcements that are over 1 week old, once per day"""
-        await remove_old_announcements(self.client.db_session)
+        async with self.client.db_session as session:
+            await remove_old_announcements(session)
 
     @remove_old_ufora_announcements.before_loop
     async def _before_remove_old_ufora_announcements(self):
diff --git a/didier/data/embeds/ufora/announcements.py b/didier/data/embeds/ufora/announcements.py
index 71b3191..52d5849 100644
--- a/didier/data/embeds/ufora/announcements.py
+++ b/didier/data/embeds/ufora/announcements.py
@@ -12,6 +12,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 import settings
 from database.crud import ufora_announcements as crud
 from database.models import UforaCourse
+from didier.utils.types.datetime import int_to_weekday
+from didier.utils.types.string import leading
 
 
 @dataclass
@@ -88,8 +90,19 @@ class UforaNotification:
 
     def _get_published(self) -> str:
         """Get a formatted string that represents when this announcement was published"""
-        # TODO
-        return "Placeholder :) TODO make the functions to format this"
+        return (
+            f"{int_to_weekday(self.published_dt.weekday())} "
+            f"{leading('0', str(self.published_dt.day))}"
+            "/"
+            f"{leading('0', str(self.published_dt.month))}"
+            "/"
+            f"{self.published_dt.year} "
+            f"om {leading('0', str(self.published_dt.hour))}"
+            ":"
+            f"{leading('0', str(self.published_dt.minute))}"
+            ":"
+            f"{leading('0', str(self.published_dt.second))}"
+        )
 
 
 def parse_ids(url: str) -> Optional[tuple[int, int]]:
diff --git a/didier/didier.py b/didier/didier.py
index 0b5b457..b42dfcc 100644
--- a/didier/didier.py
+++ b/didier/didier.py
@@ -3,12 +3,13 @@ import sys
 import traceback
 
 import discord
+from discord import Message
 from discord.ext import commands
 from sqlalchemy.ext.asyncio import AsyncSession
 
 import settings
 from database.engine import DBSession
-from didier.utils.prefix import get_prefix
+from didier.utils.discord.prefix import get_prefix
 
 
 class Didier(commands.Bot):
@@ -88,6 +89,29 @@ class Didier(commands.Bot):
         """Event triggered when the bot is ready"""
         print(settings.DISCORD_READY_MESSAGE)
 
+    async def on_message(self, message: Message, /) -> None:
+        """Event triggered when a message is sent"""
+        # Ignore messages by bots
+        if message.author.bot:
+            return
+
+        # Boos react to people that say Dider
+        if "dider" in message.content.lower() and message.author.id != self.user.id:
+            await message.add_reaction(settings.DISCORD_BOOS_REACT)
+
+        # Potential custom command
+        if self._try_invoke_custom_command(message):
+            return
+
+        await self.process_commands(message)
+
+    async def _try_invoke_custom_command(self, message: Message) -> bool:
+        """Check if the message tries to invoke a custom command
+        If it does, send the reply associated with it
+        """
+        if not message.content.startswith(settings.DISCORD_CUSTOM_COMMAND_PREFIX):
+            return False
+
     async def on_command_error(self, context: commands.Context, exception: commands.CommandError, /) -> None:
         """Event triggered when a regular command errors"""
         # If developing, print everything to stdout so you don't have to
diff --git a/didier/utils/discord/__init__.py b/didier/utils/discord/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/didier/utils/discord/checks/__init__.py b/didier/utils/discord/checks/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/didier/utils/discord/checks/message_commands.py b/didier/utils/discord/checks/message_commands.py
new file mode 100644
index 0000000..e69de29
diff --git a/didier/utils/prefix.py b/didier/utils/discord/prefix.py
similarity index 100%
rename from didier/utils/prefix.py
rename to didier/utils/discord/prefix.py
diff --git a/didier/utils/types/__init__.py b/didier/utils/types/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/didier/utils/types/datetime.py b/didier/utils/types/datetime.py
new file mode 100644
index 0000000..6e5c88e
--- /dev/null
+++ b/didier/utils/types/datetime.py
@@ -0,0 +1,3 @@
+def int_to_weekday(number: int) -> str:
+    """Get the Dutch name of a weekday from the number"""
+    return ["Maandag", "Dinsdag", "Woensdag", "Donderdag", "Vrijdag", "Zaterdag", "Zondag"][number]
diff --git a/didier/utils/types/string.py b/didier/utils/types/string.py
new file mode 100644
index 0000000..773890a
--- /dev/null
+++ b/didier/utils/types/string.py
@@ -0,0 +1,21 @@
+from typing import Optional
+
+
+def leading(character: str, string: str, target_length: Optional[int] = 2) -> str:
+    """Add a leading [character] to [string] to make it length [target_length]
+    Pass None to target length to always do it, no matter the length
+    """
+    # Cast to string just in case
+    string = str(string)
+
+    # Add no matter what
+    if target_length is None:
+        return character + string
+
+    # String is already long enough
+    if len(string) >= target_length:
+        return string
+
+    frequency = (target_length - len(string)) // len(character)
+
+    return (frequency * character) + string
diff --git a/settings.py b/settings.py
index ee0c448..797b052 100644
--- a/settings.py
+++ b/settings.py
@@ -24,6 +24,8 @@ DISCORD_TOKEN: str = env.str("DISC_TOKEN")
 DISCORD_READY_MESSAGE: str = env.str("DISC_READY_MESSAGE", "I'M READY I'M READY I'M READY")
 DISCORD_STATUS_MESSAGE: str = env.str("DISC_STATUS_MESSAGE", "with your Didier Dinks.")
 DISCORD_TEST_GUILDS: list[int] = env.list("DISC_TEST_GUILDS", [], subcast=int)
+DISCORD_BOOS_REACT: str = env.str("DISC_BOOS_REACT", "<:boos:629603785840263179>")
+DISCORD_CUSTOM_COMMAND_PREFIX: str = env.str("DISC_CUSTOM_COMMAND_PREFIX", "?")
 UFORA_ANNOUNCEMENTS_CHANNEL: Optional[int] = env.int("UFORA_ANNOUNCEMENTS_CHANNEL", None)
 
 """API Keys"""
diff --git a/tests/conftest.py b/tests/conftest.py
index 1ae9878..a74ba4c 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,5 +1,5 @@
-import os
 from typing import AsyncGenerator
+from unittest.mock import MagicMock
 
 import pytest
 
@@ -7,6 +7,7 @@ from alembic import command, config
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from database.engine import engine
+from didier import Didier
 
 
 @pytest.fixture(scope="session")
@@ -38,3 +39,16 @@ async def database_session(tables) -> AsyncGenerator[AsyncSession, None]:
         await transaction.rollback()
 
     await connection.close()
+
+
+@pytest.fixture
+def mock_client() -> Didier:
+    """Fixture to get a mock Didier instance
+    The mock uses 0 as the id
+    """
+    mock_client = MagicMock()
+    mock_user = MagicMock()
+    mock_user.id = 0
+    mock_client.user = mock_user
+
+    return mock_client
diff --git a/tests/test_database/__init__.py b/tests/test_database/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_database/test_crud/__init__.py b/tests/test_database/test_crud/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_database/test_crud/test_custom_commands.py b/tests/test_database/test_crud/test_custom_commands.py
new file mode 100644
index 0000000..5f41983
--- /dev/null
+++ b/tests/test_database/test_crud/test_custom_commands.py
@@ -0,0 +1,98 @@
+import pytest
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from database.crud import custom_commands as crud
+from database.exceptions.constraints import DuplicateInsertException
+from database.models import CustomCommand, CustomCommandAlias
+
+
+async def test_create_command_non_existing(database_session: AsyncSession):
+    """Test creating a new command when it doesn't exist yet"""
+    await crud.create_command(database_session, "name", "response")
+
+    commands = (await database_session.execute(select(CustomCommand))).scalars().all()
+    assert len(commands) == 1
+    assert commands[0].name == "name"
+
+
+async def test_create_command_duplicate_name(database_session: AsyncSession):
+    """Test creating a command when the name already exists"""
+    await crud.create_command(database_session, "name", "response")
+
+    with pytest.raises(DuplicateInsertException):
+        await crud.create_command(database_session, "name", "other response")
+
+
+async def test_create_command_name_is_alias(database_session: AsyncSession):
+    """Test creating a command when the name is taken by an alias"""
+    await crud.create_command(database_session, "name", "response")
+    await crud.create_alias(database_session, "name", "n")
+
+    with pytest.raises(DuplicateInsertException):
+        await crud.create_command(database_session, "n", "other response")
+
+
+async def test_create_alias_non_existing(database_session: AsyncSession):
+    """Test creating an alias when the name is still free"""
+    command = await crud.create_command(database_session, "name", "response")
+    await crud.create_alias(database_session, command.name, "n")
+
+    await database_session.refresh(command)
+    assert len(command.aliases) == 1
+    assert command.aliases[0].alias == "n"
+
+
+async def test_create_alias_duplicate(database_session: AsyncSession):
+    """Test creating an alias when another alias already has this name"""
+    command = await crud.create_command(database_session, "name", "response")
+    await crud.create_alias(database_session, command.name, "n")
+
+    with pytest.raises(DuplicateInsertException):
+        await crud.create_alias(database_session, command.name, "n")
+
+
+async def test_create_alias_is_command(database_session: AsyncSession):
+    """Test creating an alias when the name is taken by a command"""
+    await crud.create_command(database_session, "n", "response")
+    command = await crud.create_command(database_session, "name", "response")
+
+    with pytest.raises(DuplicateInsertException):
+        await crud.create_alias(database_session, command.name, "n")
+
+
+async def test_create_alias_match_by_alias(database_session: AsyncSession):
+    """Test creating an alias for a command when matching the name to another alias"""
+    command = await crud.create_command(database_session, "name", "response")
+    await crud.create_alias(database_session, command.name, "a1")
+    alias = await crud.create_alias(database_session, "a1", "a2")
+    assert alias.command == command
+
+
+async def test_get_command_by_name_exists(database_session: AsyncSession):
+    """Test getting a command by name"""
+    await crud.create_command(database_session, "name", "response")
+    command = await crud.get_command(database_session, "name")
+    assert command is not None
+
+
+async def test_get_command_by_cleaned_name(database_session: AsyncSession):
+    """Test getting a command by the cleaned version of the name"""
+    command = await crud.create_command(database_session, "CAPITALIZED NAME WITH SPACES", "response")
+    found = await crud.get_command(database_session, "capitalizednamewithspaces")
+    assert command == found
+
+
+async def test_get_command_by_alias(database_session: AsyncSession):
+    """Test getting a command by an alias"""
+    command = await crud.create_command(database_session, "name", "response")
+    await crud.create_alias(database_session, command.name, "a1")
+    await crud.create_alias(database_session, command.name, "a2")
+
+    found = await crud.get_command(database_session, "a1")
+    assert command == found
+
+
+async def test_get_command_non_existing(database_session: AsyncSession):
+    """Test getting a command when it doesn't exist"""
+    assert await crud.get_command(database_session, "name") is None
diff --git a/tests/test_didier/__init__.py b/tests/test_didier/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_didier/test_utils/__init__.py b/tests/test_didier/test_utils/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_didier/test_utils/test_discord/__init__.py b/tests/test_didier/test_utils/test_discord/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_didier/test_utils/test_discord/test_prefix.py b/tests/test_didier/test_utils/test_discord/test_prefix.py
new file mode 100644
index 0000000..d49e8e3
--- /dev/null
+++ b/tests/test_didier/test_utils/test_discord/test_prefix.py
@@ -0,0 +1,84 @@
+from unittest.mock import MagicMock
+
+from didier import Didier
+from didier.utils.discord.prefix import get_prefix
+
+
+def test_get_prefix_didier(mock_client: Didier):
+    """Test the "didier" prefix"""
+    mock_message = MagicMock()
+    mock_message.content = "didier test"
+    assert get_prefix(mock_client, mock_message) == "didier "
+
+
+def test_get_prefix_didier_cased(mock_client: Didier):
+    """Test the "didier" prefix with random casing"""
+    mock_message = MagicMock()
+    mock_message.content = "Didier test"
+    assert get_prefix(mock_client, mock_message) == "Didier "
+
+    mock_message = MagicMock()
+    mock_message.content = "DIDIER test"
+    assert get_prefix(mock_client, mock_message) == "DIDIER "
+
+    mock_message = MagicMock()
+    mock_message.content = "DiDiEr test"
+    assert get_prefix(mock_client, mock_message) == "DiDiEr "
+
+
+def test_get_prefix_default(mock_client: Didier):
+    """Test the fallback prefix (used when nothing matched)"""
+    mock_message = MagicMock()
+    mock_message.content = "random message"
+    assert get_prefix(mock_client, mock_message) == "didier"
+
+
+def test_get_prefix_big_d(mock_client: Didier):
+    """Test the "big d" prefix"""
+    mock_message = MagicMock()
+    mock_message.content = "big d test"
+    assert get_prefix(mock_client, mock_message) == "big d "
+
+
+def test_get_prefix_big_d_cased(mock_client: Didier):
+    """Test the "big d" prefix with random casing"""
+    mock_message = MagicMock()
+    mock_message.content = "Big d test"
+    assert get_prefix(mock_client, mock_message) == "Big d "
+
+    mock_message = MagicMock()
+    mock_message.content = "Big D test"
+    assert get_prefix(mock_client, mock_message) == "Big D "
+
+    mock_message = MagicMock()
+    mock_message.content = "BIG D test"
+    assert get_prefix(mock_client, mock_message) == "BIG D "
+
+
+def test_get_prefix_mention_username(mock_client: Didier):
+    """Test the @mention prefix when mentioned by username"""
+    mock_message = MagicMock()
+    prefix = f"<@{mock_client.user.id}> "
+    mock_message.content = f"{prefix}test"
+
+    assert get_prefix(mock_client, mock_message) == prefix
+
+
+def test_get_prefix_mention_nickname(mock_client: Didier):
+    """Test the @mention prefix when mentioned by server nickname"""
+    mock_message = MagicMock()
+    prefix = f"<@!{mock_client.user.id}> "
+    mock_message.content = f"{prefix}test"
+
+    assert get_prefix(mock_client, mock_message) == prefix
+
+
+def test_get_prefix_whitespace(mock_client: Didier):
+    """Test that variable whitespace doesn't matter"""
+    mock_message = MagicMock()
+    mock_message.content = "didiertest"
+    assert get_prefix(mock_client, mock_message) == "didier"
+
+    mock_message = MagicMock()
+    mock_message.content = "didier  test"
+    assert get_prefix(mock_client, mock_message) == "didier  "
diff --git a/tests/test_dummy.py b/tests/test_dummy.py
deleted file mode 100644
index 569bcda..0000000
--- a/tests/test_dummy.py
+++ /dev/null
@@ -1,2 +0,0 @@
-def test_dummy(tables):
-    assert True