distbuild: Add a test to ensure JsonMachine is robust

This is important to avoid distbuild processes crashing (or worse) if
they are sent unexpected input.

2 files changed, 75 insertions, 1 deletions

diff --git a/distbuild/jm_tests.py b/distbuild/jm_tests.py
new file mode 100644
index 00000000..87bf1b51
--- /dev/null
+++ b/distbuild/jm_tests.py
@@ -0,0 +1,75 @@
+# coding=utf8
+# mainloop/jm_tests.py -- testcases for JSON-parsing state machine abstraction
+#
+# Copyright (C) 2015  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA..
+
+
+import contextlib
+import logging
+import socket
+import unittest
+
+import distbuild
+
+
+class JsonMachineTests(unittest.TestCase):
+    def setUp(self):
+        self.loop = distbuild.MainLoop()
+
+    @contextlib.contextmanager
+    def listening_json_machine(self, port):
+        '''Return a writable socket connected to an example JSON machine.
+
+        This example uses the code path that listens for incoming build jobs
+        from remote machines running `morph distbuild`.
+
+        '''
+        listener = distbuild.ListenServer(
+            'localhost', port, distbuild.InitiatorConnection, [None, None])
+        self.loop.add_state_machine(listener)
+
+        listen_socket = socket.socket()
+        try:
+            listen_socket.connect(('localhost', port))
+            self.loop._run_once()
+            yield listen_socket
+        finally:
+            logging.info('Shutting down test connection handler')
+            listen_socket.shutdown(socket.SHUT_RDWR)
+            listener.close()
+            self.loop.run()
+
+    def test_invalid_input(self):
+        '''Distbuild processes must be robust against invalid input.
+
+        Anyone can write to the port that listens for connections from the
+        `morph distbuild` command. It should not be possible to break the
+        distbuild controller by sending it unexpected input.
+
+        '''
+        def send_and_process(string):
+            sock.sendall(string + '\n')
+            self.loop._run_once()
+
+        invalid_inputs = [
+            'fooin',
+            '{ "foo": "bar" }',
+            bytearray([1, 185, 5, 53]),
+        ]
+
+        with self.listening_json_machine(7979) as sock:
+            for message in invalid_inputs:
+                send_and_process(message)
diff --git a/without-test-modules b/without-test-modules
index 530deb4f..584e603b 100644
--- a/without-test-modules
+++ b/without-test-modules
@@ -40,7 +40,6 @@ distbuild/helper_router.py
 distbuild/idgen.py
 distbuild/initiator.py
 distbuild/initiator_connection.py
-distbuild/jm.py
 distbuild/json_router.py
 distbuild/mainloop.py
 distbuild/protocol.py