diff --git a/src/wormhole/cli/cmd_ssh.py b/src/wormhole/cli/cmd_ssh.py
index 6b5c4ee..715f0bc 100644
--- a/src/wormhole/cli/cmd_ssh.py
+++ b/src/wormhole/cli/cmd_ssh.py
@@ -8,6 +8,8 @@ import click
 
 from .. import xfer_util
 
+class PubkeyError(Exception):
+    pass
 
 def find_public_key(hint=None):
     """
@@ -23,11 +25,11 @@ def find_public_key(hint=None):
         hint = expanduser('~/.ssh/')
     else:
         if not exists(hint):
-            raise RuntimeError("Can't find '{}'".format(hint))
+            raise PubkeyError("Can't find '{}'".format(hint))
 
     pubkeys = [f for f in os.listdir(hint) if f.endswith('.pub')]
     if len(pubkeys) == 0:
-        raise RuntimeError("No public keys in '{}'".format(hint))
+        raise PubkeyError("No public keys in '{}'".format(hint))
     elif len(pubkeys) > 1:
         got_key = False
         while not got_key:
diff --git a/src/wormhole/test/test_ssh.py b/src/wormhole/test/test_ssh.py
new file mode 100644
index 0000000..b81be35
--- /dev/null
+++ b/src/wormhole/test/test_ssh.py
@@ -0,0 +1,59 @@
+import os, io
+import mock
+from twisted.trial import unittest
+from ..cli import cmd_ssh
+
+OTHERS = ["config", "config~", "known_hosts", "known_hosts~"]
+
+class FindPubkey(unittest.TestCase):
+    def test_find_one(self):
+        files = OTHERS + ["id_rsa.pub", "id_rsa"]
+        pubkey_data = b"ssh-rsa AAAAkeystuff email@host\n"
+        pubkey_file = io.BytesIO(pubkey_data)
+        with mock.patch("wormhole.cli.cmd_ssh.exists", return_value=True):
+            with mock.patch("os.listdir", return_value=files) as ld:
+                with mock.patch("wormhole.cli.cmd_ssh.open",
+                                return_value=pubkey_file):
+                    res = cmd_ssh.find_public_key()
+        self.assertEqual(ld.mock_calls,
+                         [mock.call(os.path.expanduser("~/.ssh/"))])
+        self.assertEqual(len(res), 3, res)
+        kind, keyid, pubkey = res
+        self.assertEqual(kind, "ssh-rsa")
+        self.assertEqual(keyid, "email@host")
+        self.assertEqual(pubkey, pubkey_data)
+
+    def test_find_none(self):
+        files = OTHERS # no pubkey
+        with mock.patch("wormhole.cli.cmd_ssh.exists", return_value=True):
+            with mock.patch("os.listdir", return_value=files):
+                e = self.assertRaises(cmd_ssh.PubkeyError,
+                                      cmd_ssh.find_public_key)
+        dot_ssh = os.path.expanduser("~/.ssh/")
+        self.assertEqual(str(e), "No public keys in '{}'".format(dot_ssh))
+
+    def test_bad_hint(self):
+        with mock.patch("wormhole.cli.cmd_ssh.exists", return_value=False):
+            e = self.assertRaises(cmd_ssh.PubkeyError,
+                                  cmd_ssh.find_public_key,
+                                  hint="bogus/path")
+        self.assertEqual(str(e), "Can't find 'bogus/path'")
+
+
+    def test_find_multiple(self):
+        files = OTHERS + ["id_rsa.pub", "id_rsa", "id_dsa.pub", "id_dsa"]
+        pubkey_data = b"ssh-rsa AAAAkeystuff email@host\n"
+        pubkey_file = io.BytesIO(pubkey_data)
+        with mock.patch("wormhole.cli.cmd_ssh.exists", return_value=True):
+            with mock.patch("os.listdir", return_value=files):
+                responses = iter(["frog", "NaN", "-1", "0"])
+                with mock.patch("click.prompt",
+                                side_effect=lambda p: next(responses)):
+                    with mock.patch("wormhole.cli.cmd_ssh.open",
+                                    return_value=pubkey_file):
+                        res = cmd_ssh.find_public_key()
+        self.assertEqual(len(res), 3, res)
+        kind, keyid, pubkey = res
+        self.assertEqual(kind, "ssh-rsa")
+        self.assertEqual(keyid, "email@host")
+        self.assertEqual(pubkey, pubkey_data)
diff --git a/src/wormhole/test/test_xfer_util.py b/src/wormhole/test/test_xfer_util.py
new file mode 100644
index 0000000..1c08f3a
--- /dev/null
+++ b/src/wormhole/test/test_xfer_util.py
@@ -0,0 +1,49 @@
+from twisted.trial import unittest
+from twisted.internet import reactor, defer
+from twisted.internet.defer import inlineCallbacks
+from .. import xfer_util
+from .common import ServerBase
+
+APPID = u"appid"
+
+class Xfer(ServerBase, unittest.TestCase):
+    @inlineCallbacks
+    def test_xfer(self):
+        code = u"1-code"
+        data = u"data"
+        d1 = xfer_util.send(reactor, APPID, self.relayurl, data, code)
+        d2 = xfer_util.receive(reactor, APPID, self.relayurl, code)
+        send_result = yield d1
+        receive_result = yield d2
+        self.assertEqual(send_result, None)
+        self.assertEqual(receive_result, data)
+
+    @inlineCallbacks
+    def test_on_code(self):
+        code = u"1-code"
+        data = u"data"
+        send_code = []
+        receive_code = []
+        d1 = xfer_util.send(reactor, APPID, self.relayurl, data, code,
+                            on_code=send_code.append)
+        d2 = xfer_util.receive(reactor, APPID, self.relayurl, code,
+                               on_code=receive_code.append)
+        send_result = yield d1
+        receive_result = yield d2
+        self.assertEqual(send_code, [code])
+        self.assertEqual(receive_code, [code])
+        self.assertEqual(send_result, None)
+        self.assertEqual(receive_result, data)
+
+    @inlineCallbacks
+    def test_make_code(self):
+        data = u"data"
+        got_code = defer.Deferred()
+        d1 = xfer_util.send(reactor, APPID, self.relayurl, data, code=None,
+                            on_code=got_code.callback)
+        code = yield got_code
+        d2 = xfer_util.receive(reactor, APPID, self.relayurl, code)
+        send_result = yield d1
+        receive_result = yield d2
+        self.assertEqual(send_result, None)
+        self.assertEqual(receive_result, data)