Python: the rb9704 command line, a fake modem, and the tests

rb9704 drives a 9704 on USB and the Cloudloop account behind it, moved
from WII6's host/rockblock with its project names taken out. rb9704-fake
speaks JSPR on a pty or a serial port: everything the library asks, MO in
segments with the CRC checked, MT, signal, provisioning, refusals and
failures on command.

The tests run against the fake at every level: the fake itself, the
command line, Ground Control's Python binding, the shell sample on
native_sim, and the sample on a board (test_zephyr.py, one suite through
two consoles). test_real.py makes free checks against a real modem.

python/tests/test_fakemodem.py

@@ -0,0 +1,106 @@
+"""The fake modem on its own, in this process: no serial port, no library."""
+
+import base64
+import json
+
+from rb9704tools.fakemodem import FakeModem, crc16_xmodem, with_crc
+
+
+class Wire:
+    def __init__(self, topics=(244,)):
+        self.out = []
+        self.events = []
+        self.m = FakeModem(self.out.append, self.events.append, topics)
+
+    def put(self, line):
+        self.m.feed((line + "\r").encode())
+
+    def lines(self):
+        got = [b.decode().rstrip("\r") for b in self.out]
+        self.out.clear()
+        return [(int(l.split(" ", 2)[0]), l.split(" ", 2)[1], json.loads(l.split(" ", 2)[2]))
+                for l in got]
+
+
+def test_crc_is_xmodem():
+    assert crc16_xmodem(b"123456789") == 0x31C3
+    assert with_crc(b"hello") == bytes.fromhex("68656c6c6fc362")
+
+
+def test_begin_sequence():
+    w = Wire()
+    w.put("GET apiVersion {}")
+    w.put("GET simConfig {}")
+    w.put("GET operationalState {}")
+    got = w.lines()
+    assert [(c, t) for c, t, _ in got] == [(200, "apiVersion"), (200, "simConfig"),
+                                           (200, "operationalState")]
+    assert "active_version" in got[0][2]
+    assert got[1][2]["interface"] == "internal"
+    assert got[2][2]["state"] == "active"
+
+
+def test_put_sim_config_answers_then_reports_status():
+    w = Wire()
+    w.put('PUT simConfig {"interface": "internal"}')
+    assert [(c, t) for c, t, _ in w.lines()] == [(200, "simConfig"), (299, "simStatus")]
+
+
+def test_mo_in_segments_with_crc():
+    w = Wire()
+    w.m.segment = 4
+    payload = b"hello world"
+    whole = with_crc(payload)
+    w.put('PUT messageOriginate {"topic_id":244, "message_length":%d, "request_reference":1}'
+          % len(whole))
+    got = w.lines()
+    assert got[0][:2] == (200, "messageOriginate")
+    mid = got[0][2]["message_id"]
+    asks = [got[1]]
+    while True:
+        code, target, body = asks[-1]
+        if target == "messageOriginateStatus":
+            break
+        assert (code, target) == (299, "messageOriginateSegment")
+        s, n = body["segment_start"], body["segment_length"]
+        w.put('PUT messageOriginateSegment {"topic_id":244, "message_id":%d, "segment_length":%d,'
+              ' "segment_start":%d, "data":"%s"}'
+              % (mid, n, s, base64.b64encode(whole[s:s + n]).decode()))
+        asks = [l for l in w.lines() if l[0] == 299]
+    assert asks[-1][2]["final_mo_status"] == "mo_ack_received"
+    assert "MO 244 %d %s" % (mid, payload.hex()) in w.events
+
+
+def test_mo_with_a_bad_crc():
+    w = Wire()
+    bad = b"abc\x00\x00"
+    w.put('PUT messageOriginate {"topic_id":244, "message_length":5, "request_reference":1}')
+    mid = w.lines()[0][2]["message_id"]
+    w.put('PUT messageOriginateSegment {"topic_id":244, "message_id":%d, "segment_length":5,'
+          ' "segment_start":0, "data":"%s"}' % (mid, base64.b64encode(bad).decode()))
+    status = [b for c, t, b in w.lines() if t == "messageOriginateStatus"]
+    assert status[0]["final_mo_status"] == "crc_error_in_transfer"
+    assert any(e.startswith("MOBAD 244") for e in w.events)
+
+
+def test_unprovisioned_topic_is_refused():
+    w = Wire(topics=())
+    w.put('PUT messageOriginate {"topic_id":244, "message_length":7, "request_reference":1}')
+    assert w.lines()[0][:2] == (406, "messageOriginate")
+
+
+def test_mt_segments_fit_the_library():
+    w = Wire()
+    w.m.send_mt(244, b"y" * 3000)
+    got = w.lines()
+    segs = [b for c, t, b in got if t == "messageTerminateSegment"]
+    assert all(len(s["data"]) <= 1446 for s in segs)
+    data = b"".join(base64.b64decode(s["data"]) for s in segs)
+    assert data == with_crc(b"y" * 3000)
+    assert got[-1][2]["final_mt_status"] == "complete"
+
+
+def test_unknown_target_is_404():
+    w = Wire()
+    w.put("GET nonsense {}")
+    assert w.lines()[0][:2] == (404, "nonsense")