tests/mock/logind: Add mock seat and session

Will be needed for KMS testing in KVM.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2151>

src/tests/meta-dbus-runner.py

@@ -5,6 +5,7 @@ import sys
 import os
 import fcntl
 import subprocess
+import getpass
 from collections import OrderedDict
 from dbusmock import DBusTestCase
 from dbus.mainloop.glib import DBusGMainLoop
@@ -39,12 +40,14 @@ class MutterDBusTestCase(DBusTestCase):
         (klass.mocks_manager, klass.mock_obj) = klass.start_from_local_template(
             'meta-mocks-manager', {'templates-dir': get_templates_dir()})
 
-        klass.start_from_template('logind')
+        logind = klass.start_from_template('logind')
         klass.start_from_local_template('localed')
 
         klass.system_bus_con = klass.get_dbus(system_bus=True)
         klass.session_bus_con = klass.get_dbus(system_bus=False)
 
+        klass.add_logind_session(logind)
+
         if klass.session_bus_con.name_has_owner('org.gnome.Mutter.DisplayConfig'):
             raise Exception(
                 'org.gnome.Mutter.DisplayConfig already has owner on the session bus, bailing')
@@ -101,6 +104,15 @@ class MutterDBusTestCase(DBusTestCase):
         assert klass.mocks.setdefault(mock_class, mocks) == mocks
         return mocks
 
+    @classmethod
+    def add_logind_session(klass, logind):
+        [p_mock, obj] = logind
+        mock_iface = 'org.freedesktop.DBus.Mock'
+        obj.AddSeat('seat0', dbus_interface=mock_iface)
+        obj.AddSession('dummy', 'seat0',
+            dbus.types.UInt32(os.getuid()), getpass.getuser(),
+            True, dbus_interface=mock_iface)
+
     def wrap_call(self, args):
         env = {}
         env.update(os.environ)