Add MX-T40 BLE desktop controller and protocol documentation

tests/test_link.py

@@ -0,0 +1,63 @@
+"""Exercise the connection state machine with a scripted serial peer."""
+
+import queue
+import sys
+import types
+import unittest
+from unittest.mock import patch
+
+from controller.link import Link
+
+
+class HandshakeTests(unittest.TestCase):
+    def run_peer(self, malformed=False):
+        events = queue.Queue()
+        link = Link("COM7", events)
+        packets = []
+        # Replay actual device ACK + CONNECT_INFO, then a link-complete ACK.
+        # Peer data sequence 0x1d is independent of our outbound sequence 1.
+        info = (
+            bytes.fromhex("00 bb 01 1d 00 01 02 20")
+            if malformed
+            else bytes.fromhex("00 bb 01 1d 00 0b 02 10 01 34 30 04 01 02 04 05 01 b0")
+        )
+        reads = iter(
+            (bytes.fromhex("00 bb 00 01 00 00 01"), info, bytes.fromhex("00 bb 00 02 00 00 02"))
+        )
+
+        class Peer:
+            def __enter__(self):
+                return self
+
+            def __exit__(self, *args):
+                pass
+
+            def write(self, data):
+                packets.append(data)
+                return len(data)
+
+            def read(self, size):
+                try:
+                    return next(reads)
+                except StopIteration:
+                    link.stop()
+                    return b""
+
+        with patch.dict(
+            sys.modules, {"serial": types.SimpleNamespace(Serial=lambda *a, **k: Peer())}
+        ):
+            link.run()
+        return packets, list(events.queue)
+
+    def test_waits_for_peer_before_ready(self):
+        packets, events = self.run_peer()
+        self.assertEqual([p[6:-1] for p in packets], [b"\x01", b"\x04"])
+        self.assertEqual(packets[1], bytes.fromhex("00 bb 01 02 00 01 04 08"))
+        self.assertEqual(sum(kind == "ready" for kind, _ in events), 1)
+        self.assertFalse(any(kind == "error" for kind, _ in events))
+
+    def test_malformed_info_never_enables_controls(self):
+        packets, events = self.run_peer(malformed=True)
+        self.assertEqual(len(packets), 1)
+        self.assertFalse(any(kind == "ready" for kind, _ in events))
+        self.assertTrue(any(kind == "error" for kind, _ in events))