modemmanager: Allow to add cell broadcast messages

Doing userspace development for cell broadcast messages can be tricky as
they're very rare in the wild. If one doesn't mock ModemManager one
needs to have a small GSM cell for testing.

Hence add a AddCbm() message to add cell broadcast messages to the MM
mock.

```
  mm_server.obj.AddCbm(2, 4383, f"This is a test)
```

Messages can be deleted via

```
  busctl call --system org.freedesktop.ModemManager1 /org/freedesktop/ModemManager1/Modems/8 org.freedesktop.ModemManager1.Modem.CellBroadcast Delete o /org/freedesktop/ModemManager1/Cbm/5
```

and listed via

```
  busctl call --system org.freedesktop.ModemManager1 /org/freedesktop/ModemManager1/Modems/8 org.freedesktop.ModemManager1.Modem.CellBroadcast List
```

The implemented API is sufficient to allow MMs `mmcbmmonitor` to detect
and display CBMs and also allows to test Phosh.

Signed-off-by: Guido Günther <[email protected]>

dbusmock/templates/modemmanager.py

@@ -25,8 +25,11 @@
 IS_OBJECT_MANAGER = False
 MODEM_IFACE = "org.freedesktop.ModemManager1.Modem"
 MODEM_3GPP_IFACE = "org.freedesktop.ModemManager1.Modem.Modem3gpp"
+MODEM_CELL_BROADCAST_IFACE = "org.freedesktop.ModemManager1.Modem.CellBroadcast"
 MODEM_VOICE_IFACE = "org.freedesktop.ModemManager1.Modem.Voice"
 SIM_IFACE = "org.freedesktop.ModemManager1.Sim"
+CBM_IFACE = "org.freedesktop.ModemManager1.Cbm"
+SIMPLE_MODEM_PATH = "/org/freedesktop/ModemManager1/Modems/8"
 
 
 class MMModemMode:
@@ -123,6 +126,31 @@ def load(mock, parameters):
     mock.AddMethod(OBJECT_MANAGER_IFACE, "GetManagedObjects", "", "a{oa{sa{sv}}}", code)
 
 
+def listCbm(_):
+    paths = []
+    for path in mockobject.objects:
+        if path.startswith("/org/freedesktop/ModemManager1/Cbm/"):
+            paths.append(dbus.ObjectPath(path))
+    return paths
+
+
+def deleteCbm(self, cbm_path):
+    obj = mockobject.objects.get(cbm_path)
+    if obj is None:
+        return
+
+    modem_obj = mockobject.objects[SIMPLE_MODEM_PATH]
+    self.RemoveObject(cbm_path)
+    modem_obj.EmitSignal(
+        MODEM_CELL_BROADCAST_IFACE,
+        "Deleted",
+        "o",
+        [
+            cbm_path,
+        ],
+    )
+
+
 @dbus.service.method(MOCK_IFACE, in_signature="", out_signature="ss")
 def AddSimpleModem(self):
     """Convenience method to add a simple Modem object
@@ -131,7 +159,7 @@ def AddSimpleModem(self):
 
     Returns the new object path.
     """
-    modem_path = "/org/freedesktop/ModemManager1/Modems/8"
+    modem_path = SIMPLE_MODEM_PATH
     sim_path = "/org/freedesktop/ModemManager1/SIM/2"
     manager = mockobject.objects[MAIN_OBJ]
 
@@ -166,6 +194,16 @@ def AddSimpleModem(self):
     modem = mockobject.objects[modem_path]
     modem.AddProperties(MODEM_3GPP_IFACE, modem_3gpp_props)
 
+    modem_cell_broadcast_props = {
+        "CellBroadcasts": dbus.Array([], signature="o"),
+    }
+    modem_cell_broadcast_methods = [
+        ("List", "", "ao", listCbm),
+        ("Delete", "o", "", deleteCbm),
+    ]
+    modem.AddProperties(MODEM_CELL_BROADCAST_IFACE, modem_cell_broadcast_props)
+    modem.AddMethods(MODEM_CELL_BROADCAST_IFACE, modem_cell_broadcast_methods)
+
     modem_voice_props = {
         "Calls": dbus.Array([], signature="o"),
         "EmergencyOnly": False,
@@ -188,6 +226,7 @@ def AddSimpleModem(self):
             {
                 MODEM_IFACE: modem_props,
                 MODEM_3GPP_IFACE: modem_3gpp_props,
+                MODEM_CELL_BROADCAST_IFACE: modem_cell_broadcast_props,
                 MODEM_VOICE_IFACE: modem_voice_props,
             },
         ],
@@ -201,3 +240,44 @@ def AddSimpleModem(self):
     self.AddObject(sim_path, SIM_IFACE, sim_props, [])
 
     return (modem_path, sim_path)
+
+
+@dbus.service.method(MOCK_IFACE, in_signature="uus", out_signature="s")
+def AddCbm(self, state, channel, text):
+    """Convenience method to add a cell broadcast message
+
+    Returns the new object path.
+    """
+    n = 1
+    while mockobject.objects.get(f"/org/freedesktop/ModemManager1/Cbm/{n}") is not None:
+        n += 1
+    cbm_path = f"/org/freedesktop/ModemManager1/Cbm/{n}"
+
+    cbm_props = {
+        "State": dbus.UInt32(state),
+        "Channel": dbus.UInt32(channel),
+        "Text": dbus.String(text),
+        "MessageCode": dbus.UInt32(0),
+        "Update": dbus.UInt32(0),
+    }
+    self.AddObject(cbm_path, CBM_IFACE, cbm_props, [])
+
+    modem_obj = mockobject.objects[SIMPLE_MODEM_PATH]
+    paths = listCbm(self)
+    modem_obj.UpdateProperties(
+        MODEM_CELL_BROADCAST_IFACE,
+        {
+            "CellBroadcasts": dbus.Array(paths),
+        },
+    )
+
+    modem_obj.EmitSignal(
+        MODEM_CELL_BROADCAST_IFACE,
+        "Added",
+        "o",
+        [
+            dbus.ObjectPath(cbm_path),
+        ],
+    )
+
+    return cbm_path

tests/test_modemmanager.py

@@ -21,7 +21,11 @@
 
 dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
 
+mmcli_has_cbm_support = False
 have_mmcli = shutil.which("mmcli")
+if have_mmcli:
+    out = subprocess.run(["mmcli", "--help"], capture_output=True, text=True)  # pylint: disable=subprocess-run-check
+    mmcli_has_cbm_support = "--help-cell-broadcast" in out.stdout
 
 
 class TestModemManagerBase(dbusmock.DBusTestCase):
@@ -136,6 +140,18 @@ def test_voice_status(self):
         self.run_mmcli(["-m", "any", "--voice-status"])
         self.assertOutputContainsLine("emergency only: no\n")
 
+    @unittest.skipUnless(mmcli_has_cbm_support, "mmcli has no CBM suppot")
+    def test_cbm(self):
+        self.p_obj.AddSimpleModem()
+        self.p_obj.AddCbm(2, 4383, "This is a test")
+        self.run_mmcli(["-m", "any", "--cell-broadcast-list-cbm"])
+        self.assertOutputEquals(
+            [
+                "    /org/freedesktop/ModemManager1/Cbm/1 (received)",
+                "",
+            ]
+        )
+
 
 if __name__ == "__main__":
     # avoid writing to stderr