diff --git a/bot/blowfish.py b/bot/blowfish.py
index d0862a9..84feab1 100644
--- a/bot/blowfish.py
+++ b/bot/blowfish.py
@@ -514,8 +514,7 @@ def encrypt(key, plaintext):
 
 def decrypt(key, cyphertext):
     """Decrypt the result of encrypt() using the original key, or raise
-    IncorrectKeyError(). If the cyphertext is malformed, raise
-    BadCyphertextError()."""
+    DecryptionError()."""
     cypher = Blowfish(key)
 
     try:
diff --git a/bot/commands/calc.py b/bot/commands/calc.py
index 0fc0fbd..9fcb63a 100644
--- a/bot/commands/calc.py
+++ b/bot/commands/calc.py
@@ -12,7 +12,7 @@ class Command(BaseCommand):
 
     def process(self, data):
         if not data.args:
-            self.connection.reply(data, "What do you want me to calculate?")
+            self.connection.reply(data, "what do you want me to calculate?")
             return
 
         query = ' '.join(data.args)
diff --git a/bot/commands/help.py b/bot/commands/help.py
index 5bb9e3d..b35d205 100644
--- a/bot/commands/help.py
+++ b/bot/commands/help.py
@@ -29,7 +29,7 @@ class Command(BaseCommand):
 
         # Create a dummy message to test which commands pick up the user's
         # input:
-        dummy = Data("PRIVMSG #fake-channel :Fake messsage!".split())
+        dummy = Data(":foo!bar@example.com PRIVMSG #channel :msg!".split())
         dummy.command = command.lower()
         dummy.is_command = True
 
diff --git a/tests/support.py b/tests/support.py
new file mode 100644
index 0000000..a2dadb5
--- /dev/null
+++ b/tests/support.py
@@ -0,0 +1,96 @@
+# -*- coding: utf-8  -*-
+
+"""
+EarwigBot's Unit Test Support
+
+This module provides some support code for unit tests.
+
+Importing this module will "fix" your path so that EarwigBot code from bot/ can
+be imported normally.
+
+CommandTestCase is a subclass of unittest.TestCase that provides setUp() for
+creating a fake connection and some other helpful methods. It uses 
+FakeConnection, a subclass of classes.Connection, but with an internal string
+instead of a socket for data.
+"""
+
+from os import path
+import re
+import sys
+from unittest import TestCase
+
+root_dir = path.split(path.dirname(path.abspath(__file__)))[0]
+code_dir = path.join(root_dir, "bot")
+sys.path.insert(0, code_dir)
+
+from classes import Connection, Data
+
+class CommandTestCase(TestCase):
+    re_sender = re.compile(":(.*?)!(.*?)@(.*?)\Z")
+
+    def setUp(self, command):
+        self.connection = FakeConnection()
+        self.connection.connect()
+        self.command = command(self.connection)
+
+    def get_single(self):
+        data = self.connection.get().split("\n")
+        line = data.pop(0)
+        for remaining in data[1:]:
+            self.connection.send(remaining)
+        return line
+
+    def assertSent(self, msg):
+        line = self.get_single()
+        self.assertEqual(line, msg)
+
+    def assertSentIn(self, msgs):
+        line = self.get_single()
+        self.assertIn(line, msgs)
+
+    def assertSaid(self, msg):
+        self.assertSent("PRIVMSG #channel :{0}".format(msg))
+
+    def assertSaidIn(self, msgs):
+        msgs = ["PRIVMSG #channel :{0}".format(msg) for msg in msgs]
+        self.assertSentIn(msgs)
+
+    def assertReply(self, msg):
+        self.assertSaid("\x02Foo\x0F: {0}".format(msg))
+
+    def assertReplyIn(self, msgs):
+        msgs = ["\x02Foo\x0F: {0}".format(msg) for msg in msgs]
+        self.assertSaidIn(msgs)
+
+    def maker(self, line, chan, msg=None):
+        data = Data(line)
+        data.nick, data.ident, data.host = self.re_sender.findall(line[0])[0]
+        if msg is not None:
+            data.msg = msg
+        data.chan = chan
+        data.parse_args()
+        return data
+
+    def make_msg(self, command, *args):
+        line = ":Foo!bar@example.com PRIVMSG #channel :!{0}".format(command)
+        line = line.strip().split()
+        line.extend(args)
+        return self.maker(line, line[2], " ".join(line[3:])[1:])
+
+    def make_join(self):
+        line = ":Foo!bar@example.com JOIN :#channel".strip().split()
+        return self.maker(line, line[2][1:])
+
+class FakeConnection(Connection):
+    def connect(self):
+        self._buffer = ""
+
+    def close(self):
+        pass
+
+    def get(self, size=4096):
+        data, self._buffer = self._buffer, ""
+        return data
+
+    def send(self, msg):
+        self._buffer += msg + "\n"
diff --git a/tests/test_blowfish.py b/tests/test_blowfish.py
new file mode 100644
index 0000000..9eb6184
--- /dev/null
+++ b/tests/test_blowfish.py
@@ -0,0 +1,77 @@
+# -*- coding: utf-8  -*-
+
+import unittest
+import random
+import string
+
+import support
+import blowfish
+
+class TestBlowfish(unittest.TestCase):
+
+    def test_key_sizes(self):
+        b = blowfish.Blowfish
+        e = blowfish.KeyLengthError
+
+        self.assertRaisesRegexp(e, "no key given", b, None)
+        self.assertRaisesRegexp(e, "no key given", b, "")
+        self.assertRaisesRegexp(e, "at least", b, " " * 3)
+        self.assertRaisesRegexp(e, "at least", b, "1234567")
+        self.assertRaisesRegexp(e, "less than", b, " " * 57)
+        self.assertRaisesRegexp(e, "less than", b, "x" * 60)
+        self.assertRaisesRegexp(e, "less than", b, "1" * 128)
+
+        b("These keys should be valid!")
+        b("'!\"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'")
+        b(" " * 8)
+        b(" " * 56)
+
+    def test_symmetry(self):
+        def _test_symmetry():
+            key_length = random.randint(8, 56)
+            msg_length = random.randint(0, 4096)
+            key = "".join([random.choice(chars) for i in xrange(key_length)])
+            msg = "".join([random.choice(chars) for i in xrange(msg_length)])
+            
+            enc = blowfish.encrypt(key, msg)
+            dec = blowfish.decrypt(key, enc)
+            self.assertEqual(dec, msg)
+
+        chars = string.letters + string.digits + string.punctuation
+        for i in xrange(8):
+            _test_symmetry()
+
+    def test_encryption(self):
+        tests = [
+            ("example_key", "Hello, I'm a message!", "8411a21574431176cdff9a549d27962c616014a9fe2a1fe3b0c7a823e8a1e635"),
+            ("another random key", "Another random message! :(", "2cdcdf4e53145897ed9d4cc2433aa4bf59b087b14d0ac76a13eff12dec00e60c40857109da3c7bc4"),
+            ("HEY LET'S TRY |°|_J|\|C7|_J/-\\710|\|", "Yes, that was my fail attempt at 1337SP33K >_>", "d4901c7c0956da3b9507cd81cd3c880d7cda25ec6c5336deb9280ce67c099eeddf7c7e052f3a946afbd92c32ae0ab8dbdd875bc5a3f0d686")
+        ]
+
+        for test in tests:
+            self.assertEquals(blowfish.encrypt(test[0], test[1]), test[2])
+
+    def test_decryption(self):
+        tests = [
+            ("blah blah blah", "ab35274c66bb8b3b03c9bd26ab477f3de06857e1d369ad35", "Blah, blah, blah!"),
+            ("random key", "eb2fe950c5c12bca9534ffdd27631f33d3e4bcae53a634b4aaa09f9fe14c4386", "Random message as well!"),
+            ("Okay, now I'm just desperate", "0da74e1cec41e8323da93d0c05bcf3919084130cef93021991da174fd97f8e1c9b125ed5263b41a8", "Unit testing is SO FUN ISN'T IT.")
+        ]
+
+        for test in tests:
+            self.assertEquals(blowfish.decrypt(test[0], test[1]), test[2])
+
+    def test_decryption_exceptions(self):
+        d = blowfish.decrypt
+        e = blowfish.BlowfishError
+
+        e1 = "could not be decoded"
+        e2 = "cannot be broken into 8-byte blocks"
+        e3 = "key is incorrect"
+
+        self.assertRaisesRegexp(e, e1, d, "some_key", "arr!")
+        self.assertRaisesRegexp(e, e2, d, "some_key", "abcd")
+        self.assertRaisesRegexp(e, e3, d, "some_key", "abcdabcdabcdabcd")
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)
diff --git a/tests/test_calc.py b/tests/test_calc.py
new file mode 100644
index 0000000..981fda3
--- /dev/null
+++ b/tests/test_calc.py
@@ -0,0 +1,39 @@
+# -*- coding: utf-8  -*-
+
+import unittest
+
+import support
+from commands.calc import Command
+
+class TestCalc(support.CommandTestCase):
+
+    def setUp(self):
+        super(TestCalc, self).setUp(Command)
+
+    def test_check(self):
+        self.assertFalse(self.command.check(self.make_msg("bloop")))
+        self.assertFalse(self.command.check(self.make_join()))
+
+        self.assertTrue(self.command.check(self.make_msg("calc")))
+        self.assertTrue(self.command.check(self.make_msg("CALC", "foo")))
+
+    def test_ignore_empty(self):
+        self.command.process(self.make_msg("calc"))
+        self.assertReply("what do you want me to calculate?")
+
+    def test_maths(self):
+        tests = [
+            ("2 + 2", "2 + 2 = 4"),
+            ("13 * 5", "13 * 5 = 65"),
+            ("80 / 42", "80 / 42 = 40/21 (approx. 1.9047619047619047)"),
+            ("2/0", "2/0 = undef"),
+            ("π", "π = 3.141592653589793238"),
+        ]
+
+        for test in tests:
+            q = test[0].strip().split()
+            self.command.process(self.make_msg("calc", *q))
+            self.assertReply(test[1])
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)
diff --git a/tests/test_test.py b/tests/test_test.py
new file mode 100644
index 0000000..540e1eb
--- /dev/null
+++ b/tests/test_test.py
@@ -0,0 +1,29 @@
+# -*- coding: utf-8  -*-
+
+import unittest
+
+import support
+from commands.test import Command
+
+class TestTest(support.CommandTestCase):
+
+    def setUp(self):
+        super(TestTest, self).setUp(Command)
+
+    def test_check(self):
+        self.assertFalse(self.command.check(self.make_msg("bloop")))
+        self.assertFalse(self.command.check(self.make_join()))
+
+        self.assertTrue(self.command.check(self.make_msg("test")))
+        self.assertTrue(self.command.check(self.make_msg("TEST", "foo")))
+
+    def test_process(self):
+        def _test():
+            self.command.process(self.make_msg("test"))
+            self.assertSaidIn(["Hey \x02Foo\x0F!", "'sup \x02Foo\x0F?"])
+
+        for i in xrange(64):
+            _test()
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)