tests/runner: Add 'resize_monitor' metatest command

This will allow tests to change monitor resolution. The first argument
is the monitor ID; there is always one monitor added by default, and it
has the id 0. It's currently not possible to add more monitors, so
passing '0' is the only valid way to resize monitors.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2554>

src/backends/meta-virtual-monitor.h

@@ -70,6 +70,7 @@ void meta_virtual_monitor_info_free (MetaVirtualMonitorInfo *info);
 
 MetaCrtc * meta_virtual_monitor_get_crtc (MetaVirtualMonitor *virtual_monitor);
 
+META_EXPORT_TEST
 MetaCrtcMode * meta_virtual_monitor_get_crtc_mode (MetaVirtualMonitor *virtual_monitor);
 
 META_EXPORT_TEST

src/tests/test-runner.c

@@ -989,6 +989,29 @@ test_case_do (TestCase *test,
       if (!meta_test_client_do (client, error, argv[0], argv[2], argv[3], NULL))
         return FALSE;
     }
+  else if (strcmp (argv[0], "resize_monitor") == 0)
+    {
+      MetaBackend *backend = meta_context_get_backend (test->context);
+      MetaMonitorManager *monitor_manager =
+        meta_backend_get_monitor_manager (backend);
+      MetaCrtcMode *crtc_mode;
+      const MetaCrtcModeInfo *crtc_mode_info;
+
+      if (argc != 4)
+        BAD_COMMAND ("usage: %s <monitor-id> <width> <height>", argv[0]);
+
+      if (strcmp (argv[1], "0") != 0 &&
+          strcmp (argv[1], "primary") != 0)
+        BAD_COMMAND ("Unknown monitor %s", argv[1]);
+
+      crtc_mode = meta_virtual_monitor_get_crtc_mode (test->virtual_monitor);
+      crtc_mode_info = meta_crtc_mode_get_info (crtc_mode);
+      meta_virtual_monitor_set_mode (test->virtual_monitor,
+                                     atoi (argv[2]),
+                                     atoi (argv[3]),
+                                     crtc_mode_info->refresh_rate);
+      meta_monitor_manager_reload (monitor_manager);
+    }
   else
     {
       BAD_COMMAND("Unknown command %s", argv[0]);