tests/fullscreen: Add broken slow client unfullscreen view offset restoration test

src/tests/fullscreen.rs

@@ -153,3 +153,65 @@ fn windowed_fullscreen_chain() {
     "
     );
 }
+
+#[test]
+fn unfullscreen_before_fullscreen_ack_doesnt_prevent_view_offset_save_restore() {
+    let (mut f, id, _surface) = set_up();
+
+    let window2 = f.client(id).create_window();
+    let surface2 = window2.surface.clone();
+    window2.commit();
+    f.roundtrip(id);
+
+    let window2 = f.client(id).window(&surface2);
+    window2.attach_new_buffer();
+    window2.set_size(200, 200);
+    window2.ack_last_and_commit();
+    f.double_roundtrip(id);
+
+    let _ = f.client(id).window(&surface2).recent_configures();
+
+    let niri = f.niri();
+    let mapped2 = niri.layout.windows().last().unwrap().1;
+    let window2_id = mapped2.window.clone();
+
+    // The view position is at the first window.
+    assert_snapshot!(niri.layout.active_workspace().unwrap().scrolling().view_pos(), @"-16");
+
+    // Fullscreen window2 and send the configure so we can clear pending.
+    niri.layout.set_fullscreen(&window2_id, true);
+    f.double_roundtrip(id);
+
+    // Before acking, unfullscreen the column, clearing the pending fullscreen flag.
+    f.niri().layout.set_fullscreen(&window2_id, false);
+
+    // Now, window2 receives the fullscreen configure and resizes in response.
+    let window2 = f.client(id).window(&surface2);
+    assert_snapshot!(
+        window2.format_recent_configures(),
+        @"size: 1920 × 1080, bounds: 1888 × 1048, states: [Activated, Fullscreen]"
+    );
+    let (_, configure) = window2.configures_received.last().unwrap();
+    window2.set_size(configure.size.0 as u16, configure.size.1 as u16);
+    window2.ack_last_and_commit();
+    f.double_roundtrip(id);
+    f.niri_complete_animations();
+
+    // The view position is now at the fullscreen-sized window2.
+    assert_snapshot!(f.niri().layout.active_workspace().unwrap().scrolling().view_pos(), @"116");
+
+    // Now, window2 receives the unfullscreen configure and resizes in response.
+    let window2 = f.client(id).window(&surface2);
+    assert_snapshot!(
+        window2.format_recent_configures(),
+        @"size: 936 × 1048, bounds: 1888 × 1048, states: [Activated]"
+    );
+    window2.set_size(200, 200);
+    window2.ack_last_and_commit();
+    f.roundtrip(id);
+    f.niri_complete_animations();
+
+    // The view position should restore to the first window.
+    // FIXME: this currently doesn't work and sets the view position to the second window.
+    assert_snapshot!(f.niri().layout.active_workspace().unwrap().scrolling().view_pos(), @"100");
+}