diff --git a/src/net/java/sip/communicator/impl/protocol/irc/CommandFactory.java b/src/net/java/sip/communicator/impl/protocol/irc/CommandFactory.java
index 962c53eef..955fbdfdd 100644
--- a/src/net/java/sip/communicator/impl/protocol/irc/CommandFactory.java
+++ b/src/net/java/sip/communicator/impl/protocol/irc/CommandFactory.java
@@ -7,6 +7,8 @@
 package net.java.sip.communicator.impl.protocol.irc;
 
 import java.util.*;
+import java.util.Map.Entry;
+
 import net.java.sip.communicator.impl.protocol.irc.exception.*;
 import net.java.sip.communicator.util.*;
 
@@ -28,6 +30,16 @@ public class CommandFactory
     private static final Map<String, Class<? extends Command>> COMMANDS
             = new HashMap<String, Class<? extends Command>>();
 
+    /**
+     * Get an unmodifiable map of registered commands.
+     *
+     * @return returns an unmodifiable map of registered commands
+     */
+    public static Map<String, Class<? extends Command>> getCommands()
+    {
+        return Collections.unmodifiableMap(COMMANDS);
+    }
+
     /**
      * Register a new command at the factory.
      *
@@ -37,6 +49,14 @@ public class CommandFactory
     public static void registerCommand(final String command,
             final Class<? extends Command> type)
     {
+        if (command == null)
+        {
+            throw new IllegalArgumentException("command cannot be null");
+        }
+        if (type == null)
+        {
+            throw new IllegalArgumentException("type cannot be null");
+        }
         if (LOGGER.isDebugEnabled())
         {
             LOGGER.debug("Registered command '" + command + "' ("
@@ -45,6 +65,30 @@ public static void registerCommand(final String command,
         COMMANDS.put(command, type);
     }
 
+    /**
+     * Unregister a command from the factory.
+     *
+     * @param type the type to unregister
+     * @param command (optional) specify the command for which the type is
+     *            registered. This can be used to unregister only one of
+     *            multiple commands for the same implementation type.
+     */
+    public static void unregisterCommand(final Class<? extends Command> type,
+        final String command)
+    {
+        Iterator<Entry<String, Class<? extends Command>>> it =
+            COMMANDS.entrySet().iterator();
+        while (it.hasNext())
+        {
+            Entry<String, Class<? extends Command>> entry = it.next();
+            if (entry.getValue() == type
+                && (command == null || command.equals(entry.getKey())))
+            {
+                it.remove();
+            }
+        }
+    }
+
     /**
      * Instance of protocol provider service.
      */
@@ -87,9 +131,10 @@ public static void registerCommand(final String command,
     public Command createCommand(final String command)
             throws UnsupportedCommandException
     {
-        if (command == null)
+        if (command == null || command.isEmpty())
         {
-            throw new IllegalArgumentException("command cannot be null");
+            throw new IllegalArgumentException(
+                "command cannot be null or empty");
         }
         final Class<? extends Command> type = COMMANDS.get(command);
         if (type == null)
diff --git a/test/net/java/sip/communicator/impl/protocol/irc/CommandFactoryTest.java b/test/net/java/sip/communicator/impl/protocol/irc/CommandFactoryTest.java
new file mode 100644
index 000000000..165c46f41
--- /dev/null
+++ b/test/net/java/sip/communicator/impl/protocol/irc/CommandFactoryTest.java
@@ -0,0 +1,314 @@
+package net.java.sip.communicator.impl.protocol.irc;
+
+import junit.framework.*;
+import net.java.sip.communicator.impl.protocol.irc.exception.*;
+
+import org.easymock.*;
+
+public class CommandFactoryTest
+    extends TestCase
+{
+    public void testCommandsAvailable()
+    {
+        Assert.assertNotNull(CommandFactory.getCommands());
+    }
+
+    public void testRegisterNullCommand()
+    {
+        try
+        {
+            CommandFactory.registerCommand(null, new Command()
+            {
+                @Override
+                public void init(ProtocolProviderServiceIrcImpl provider,
+                    IrcConnection connection)
+                {
+                }
+
+                @Override
+                public void execute(String source, String line)
+                {
+                }
+            }.getClass());
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+    }
+
+    public void testRegisterNullType()
+    {
+        try
+        {
+            CommandFactory.registerCommand("test", null);
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+    }
+
+    public void testRegisterCorrectCommand()
+    {
+        CommandFactory.registerCommand("test", Test.class);
+        Assert.assertEquals(1,  CommandFactory.getCommands().size());
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("test"));
+        CommandFactory.unregisterCommand(Test.class, "test");
+        Assert.assertEquals(0, CommandFactory.getCommands().size());
+    }
+
+    public void testRegisterMultipleCommandsForType()
+    {
+        CommandFactory.registerCommand("test", Test.class);
+        CommandFactory.registerCommand("bla", Test.class);
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("test"));
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("bla"));
+        Assert.assertEquals(2, CommandFactory.getCommands().size());
+        CommandFactory.unregisterCommand(Test.class, null);
+        Assert.assertEquals(0,  CommandFactory.getCommands().size());
+    }
+
+    public void testUnregisterMultipleAmongOtherTypes()
+    {
+        Command anotherType = new Command() {
+
+            @Override
+            public void init(ProtocolProviderServiceIrcImpl provider,
+                IrcConnection connection)
+            {
+            }
+
+            @Override
+            public void execute(String source, String line)
+            {
+            }};
+        CommandFactory.registerCommand("test", Test.class);
+        CommandFactory.registerCommand("foo", anotherType.getClass());
+        CommandFactory.registerCommand("bla", Test.class);
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("test"));
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("bla"));
+        Assert.assertNotNull(CommandFactory.getCommands().get("foo"));
+        Assert.assertEquals(3, CommandFactory.getCommands().size());
+        CommandFactory.unregisterCommand(Test.class, null);
+        Assert.assertEquals(1, CommandFactory.getCommands().size());
+        Assert.assertNotSame(Test.class, CommandFactory.getCommands().get("foo"));
+        CommandFactory.unregisterCommand(anotherType.getClass(), null);
+    }
+
+    public void testUnregisterOneAmongMultipleSameType()
+    {
+        CommandFactory.registerCommand("test", Test.class);
+        CommandFactory.registerCommand("bla", Test.class);
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("test"));
+        Assert.assertEquals(Test.class, CommandFactory.getCommands()
+            .get("bla"));
+        Assert.assertEquals(2, CommandFactory.getCommands().size());
+        CommandFactory.unregisterCommand(Test.class, "test");
+        Assert.assertEquals(1, CommandFactory.getCommands().size());
+        Assert.assertEquals(Test.class, CommandFactory.getCommands().get("bla"));
+        CommandFactory.unregisterCommand(Test.class, null);
+    }
+
+    public static class Test implements Command
+    {
+
+        @Override
+        public void init(ProtocolProviderServiceIrcImpl provider,
+            IrcConnection connection)
+        {
+        }
+
+        @Override
+        public void execute(String source, String line)
+        {
+        }
+    }
+
+    public void testConstructionNullProvider()
+    {
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(connection);
+
+        try
+        {
+            new CommandFactory(null, connection);
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+    }
+
+    public void testConstructionNullConnection()
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        EasyMock.replay(provider);
+
+
+        try
+        {
+            new CommandFactory(provider, null);
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+    }
+
+    public void testConstruction()
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        new CommandFactory(provider, connection);
+    }
+
+    public void testNonExistingCommand()
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            factory.createCommand("test");
+            Assert.fail();
+        }
+        catch (UnsupportedCommandException e)
+        {
+        }
+    }
+
+    public void testCreateNullCommandName() throws UnsupportedCommandException
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        CommandFactory.registerCommand("test", Test.class);
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            factory.createCommand(null);
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+        CommandFactory.unregisterCommand(Test.class, null);
+    }
+
+    public void testCreateEmptyCommandName() throws UnsupportedCommandException
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        CommandFactory.registerCommand("test", Unreachable.class);
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            factory.createCommand("");
+            Assert.fail();
+        }
+        catch (IllegalArgumentException e)
+        {
+        }
+        finally
+        {
+            CommandFactory.unregisterCommand(Test.class, null);
+        }
+    }
+
+    public void testExistingCommand() throws UnsupportedCommandException
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        CommandFactory.registerCommand("test", Test.class);
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            Command cmd = factory.createCommand("test");
+            Assert.assertNotNull(cmd);
+            Assert.assertTrue(cmd instanceof Test);
+        }
+        finally
+        {
+            CommandFactory.unregisterCommand(Test.class, null);
+        }
+    }
+
+    public void testUnreachableCommand() throws UnsupportedCommandException
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        CommandFactory.registerCommand("test", Unreachable.class);
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            factory.createCommand("test");
+            Assert.fail();
+        }
+        catch (IllegalStateException e)
+        {
+        }
+        finally
+        {
+            CommandFactory.unregisterCommand(Unreachable.class, null);
+        }
+    }
+
+    public void testBadCommand() throws UnsupportedCommandException
+    {
+        ProtocolProviderServiceIrcImpl provider = EasyMock.createMock(ProtocolProviderServiceIrcImpl.class);
+        IrcConnection connection = EasyMock.createMock(IrcConnection.class);
+        EasyMock.replay(provider, connection);
+
+        CommandFactory.registerCommand("test", BadImplementation.class);
+        try
+        {
+            CommandFactory factory = new CommandFactory(provider, connection);
+            factory.createCommand("test");
+            Assert.fail();
+        }
+        catch (IllegalStateException e)
+        {
+        }
+        finally
+        {
+            CommandFactory.unregisterCommand(BadImplementation.class, null);
+        }
+    }
+
+    private static class Unreachable implements Command
+    {
+
+        @Override
+        public void init(ProtocolProviderServiceIrcImpl provider,
+            IrcConnection connection)
+        {
+        }
+
+        @Override
+        public void execute(String source, String line)
+        {
+        }
+    }
+
+    public abstract static class BadImplementation implements Command
+    {
+    }
+}