tests/dbus-runner: Allow setting custom parser state and environment

This will be useful for the installed tests runner, which for some tests
need custom actions that needs to change the environment the test run
in.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3973>

src/tests/mutter_dbusrunner.py

@@ -260,7 +260,7 @@ ret = logind_helpers.open_file_direct(major, minor)
         raise FileNotFoundError(f'Couldnt find a {template_name} template')
 
 
-def wrap_call(args, wrapper):
+def wrap_call(args, wrapper, extra_env):
     env = {}
     env.update(os.environ)
     env['NO_AT_BRIDGE'] = '1'
@@ -269,6 +269,9 @@ def wrap_call(args, wrapper):
     env['XDG_CURRENT_DESKTOP'] = ''
     env['META_DBUS_RUNNER_ACTIVE'] = '1'
 
+    if extra_env:
+        env |= extra_env
+
     if wrapper == 'gdb':
         args = ['gdb', '-ex', 'r', '-ex', 'bt full', '--args'] + args
     elif wrapper == 'rr':
@@ -281,15 +284,20 @@ def wrap_call(args, wrapper):
     return p.wait()
 
 
-def meta_run(klass):
+def meta_run(klass, extra_env=None, setup_argparse=None, handle_argparse=None):
     DBusGMainLoop(set_as_default=True)
 
     parser = argparse.ArgumentParser()
     parser.add_argument('--kvm', action='store_true', default=False)
     parser.add_argument('--launch', action='append', default=[])
     parser.add_argument('--no-isolate-dirs', action='store_true', default=False)
+    if setup_argparse:
+        setup_argparse(parser)
     (args, rest) = parser.parse_known_args(sys.argv)
 
+    if handle_argparse:
+        handle_argparse(args)
+
     rest.pop(0)
     if not rest:
         parser.error('Command or separator `--` not found')
@@ -303,12 +311,12 @@ def meta_run(klass):
         args.launch.append(launch.split(','))
 
     if args.no_isolate_dirs:
-        return meta_run_klass(klass, args, rest)
+        return meta_run_klass(klass, args, rest, extra_env)
 
     test_root = os.getenv('MUTTER_DBUS_RUNNER_TEST_ROOT')
     if test_root:
         print('Reusing MUTTER_DBUS_RUNNER_TEST_ROOT', test_root, file=sys.stderr)
-        return meta_run_klass(klass, args, rest)
+        return meta_run_klass(klass, args, rest, extra_env)
 
     with tempfile.TemporaryDirectory(prefix='mutter-testroot-',
                                      ignore_cleanup_errors=True) as test_root:
@@ -320,9 +328,9 @@ def meta_run(klass):
             os.mkdir(directory, mode=0o700)
             os.environ[env_dir] = directory
             print('Setup', env_dir, 'as', directory, file=sys.stderr)
-        return meta_run_klass(klass, args, rest)
+        return meta_run_klass(klass, args, rest, extra_env)
 
-def meta_run_klass(klass, args, rest):
+def meta_run_klass(klass, args, rest, extra_env):
     result = 1
 
     if os.getenv('META_DBUS_RUNNER_ACTIVE') == None:
@@ -333,7 +341,7 @@ def meta_run_klass(klass, args, rest):
 
         try:
             print('Running test case...', file=sys.stderr)
-            result = wrap_call(rest, wrapper)
+            result = wrap_call(rest, wrapper, extra_env)
         finally:
             MutterDBusRunner.tearDownClass()
     else:
@@ -342,7 +350,7 @@ def meta_run_klass(klass, args, rest):
                    'Not re-creating mocked environment.'),
                   file=sys.stderr)
             print('Running test case...', file=sys.stderr)
-            result = wrap_call(rest, None)
+            result = wrap_call(rest, None, extra_env)
         finally:
             pass