tests/stacking: Test always-on-top stacking and focus

Adds the command make_above to set and unset always-on-top behavior of a
window and tests stacking and focus when activating other windows and
switching workspaces.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2489>

src/tests/meson.build

@@ -442,6 +442,7 @@ stacking_tests = [
   'map-on-hotplug',
   'workspace-basic',
   'workspace-test',
+  'always-on-top',
 ]
 
 foreach stacking_test: stacking_tests

src/tests/stacking/always-on-top.metatest

@@ -0,0 +1,51 @@
+num_workspaces 2
+
+new_client 1 wayland
+create 1/1
+show 1/1
+create 1/2
+show 1/2
+create 1/3
+show 1/3
+wait
+
+assert_stacking_workspace 0 1/1 1/2 1/3
+assert_stacking_workspace 1
+assert_focused 1/3
+
+local_activate 1/1
+
+assert_stacking_workspace 0 1/2 1/3 1/1
+assert_stacking_workspace 1
+assert_focused 1/1
+
+make_above 1/3 true
+
+assert_stacking_workspace 0 1/2 1/1 1/3
+assert_stacking_workspace 1
+assert_focused 1/1
+
+local_activate 1/2
+
+assert_stacking_workspace 0 1/1 1/2 1/3
+assert_stacking_workspace 1
+assert_focused 1/2
+
+activate_workspace 1
+
+assert_stacking_workspace 0 1/1 1/2 1/3
+assert_stacking_workspace 1
+assert_focused none
+
+activate_workspace 0
+
+assert_stacking_workspace 0 1/1 1/2 1/3
+assert_stacking_workspace 1
+assert_focused 1/2
+
+make_above 1/3 false
+local_activate 1/1
+
+assert_stacking_workspace 0 1/2 1/3 1/1
+assert_stacking_workspace 1
+assert_focused 1/1

src/tests/test-runner.c

@@ -1148,6 +1148,29 @@ test_case_do (TestCase *test,
 
       meta_window_change_workspace (window, workspace);
     }
+  else if (strcmp (argv[0], "make_above") == 0)
+    {
+      if (argc != 3 ||
+          (g_ascii_strcasecmp (argv[2], "true") != 0 &&
+           g_ascii_strcasecmp (argv[2], "false") != 0))
+        BAD_COMMAND("usage: %s <client-id>/<window-id> [true|false]",
+                    argv[0]);
+
+      MetaTestClient *client;
+      const char *window_id;
+      if (!test_case_parse_window_id (test, argv[1], &client, &window_id, error))
+        return FALSE;
+
+      MetaWindow *window;
+      window = meta_test_client_find_window (client, window_id, error);
+      if (!window)
+        return FALSE;
+
+      if (g_ascii_strcasecmp (argv[2], "true") == 0)
+        meta_window_make_above (window);
+      else
+        meta_window_unmake_above (window);
+    }
   else
     {
       BAD_COMMAND("Unknown command %s", argv[0]);