tests: Skip unsupported dbus-appinfo test on GNU/Hurd for the moment

Parts of the `dbus-appinfo` test need support for converting an FD to a
path, and Hurd doesn’t currently allow that (see
https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4396#note_2279923).

Since there’s no fix for that visible in the medium term (new kernel
APIs will need to be added), skip parts of the `dbus-appinfo` test which
require that functionality for now.

This prevents the whole test from failing, and means we can usefully get
results from the parts of it which don’t depend on converting FDs to
paths.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3538

gio/tests/dbus-appinfo.c

@@ -532,6 +532,12 @@ test_portal_open_file (void)
   char *uri;
   GFakeDesktopPortalThread *thread = NULL;
 
+  if (!g_fake_desktop_portal_is_supported ())
+    {
+      g_test_skip ("fake-desktop-portal not currently supported on this platform");
+      return;
+    }
+
   /* Run a fake-desktop-portal */
   thread = g_fake_desktop_portal_thread_new (session_bus_get_address ());
   g_fake_desktop_portal_thread_run (thread);
@@ -567,6 +573,12 @@ test_portal_open_uri (void)
   const char *uri = "http://example.com";
   GFakeDesktopPortalThread *thread = NULL;
 
+  if (!g_fake_desktop_portal_is_supported ())
+    {
+      g_test_skip ("fake-desktop-portal not currently supported on this platform");
+      return;
+    }
+
   /* Run a fake-desktop-portal */
   thread = g_fake_desktop_portal_thread_new (session_bus_get_address ());
   g_fake_desktop_portal_thread_run (thread);
@@ -611,6 +623,12 @@ test_portal_open_file_async (void)
   char *uri;
   GFakeDesktopPortalThread *thread = NULL;
 
+  if (!g_fake_desktop_portal_is_supported ())
+    {
+      g_test_skip ("fake-desktop-portal not currently supported on this platform");
+      return;
+    }
+
   /* Run a fake-desktop-portal */
   thread = g_fake_desktop_portal_thread_new (session_bus_get_address ());
   g_fake_desktop_portal_thread_run (thread);
@@ -649,6 +667,12 @@ test_portal_open_uri_async (void)
   const char *uri = "http://example.com";
   GFakeDesktopPortalThread *thread = NULL;
 
+  if (!g_fake_desktop_portal_is_supported ())
+    {
+      g_test_skip ("fake-desktop-portal not currently supported on this platform");
+      return;
+    }
+
   /* Run a fake-desktop-portal */
   thread = g_fake_desktop_portal_thread_new (session_bus_get_address ());
   g_fake_desktop_portal_thread_run (thread);

gio/tests/fake-desktop-portal.c

@@ -494,3 +494,15 @@ g_fake_desktop_portal_thread_stop (GFakeDesktopPortalThread *self)
   g_cancellable_cancel (self->cancellable);
   g_thread_join (g_steal_pointer (&self->thread));
 }
+
+/* Whether fake-desktop-portal is supported on this platform. This basically
+ * means whether _g_fd_query_path() will work at runtime. */
+gboolean
+g_fake_desktop_portal_is_supported (void)
+{
+#ifdef __GNU__
+  return FALSE;
+#else
+  return TRUE;
+#endif
+}

gio/tests/fake-desktop-portal.h

@@ -33,6 +33,8 @@ const gchar *g_fake_desktop_portal_thread_get_last_request_activation_token (GFa
 void g_fake_desktop_portal_thread_run (GFakeDesktopPortalThread *self);
 void g_fake_desktop_portal_thread_stop (GFakeDesktopPortalThread *self);
 
+gboolean g_fake_desktop_portal_is_supported (void);
+
 G_END_DECLS
 
 #endif /* __FAKE_DESKTOP_PORTAL_H__ */