docking: the host stand-in needs no expect, and the label count drops with New Window

crates/ui/src/docking/native_tests.rs

@@ -58,6 +58,7 @@ fn driver(layout: Layout<u32>) -> DockDriver<u32, Content> {
     DockDriver::new(layout, Content::default()).with_style(|s| s.command_press_floats = true).with_native_host(ORIGIN)
 }
 
+#[allow(clippy::expect_used)]
 fn window(d: &DockDriver<u32, Content>, panel: u32) -> &Floating<u32> {
     d.layout.floating.iter().find(|w| w.contains(&panel)).expect("floating")
 }

crates/ui/src/docking/testing.rs

@@ -46,9 +46,11 @@ pub struct DockDriver<P, C> {
     pub float_bounds: Option<Rect>,
     /// Passed to [`DockArea::monitors`].
     pub monitors: Vec<Monitor>,
-    /// The stand-in for OS windows, from [`Self::with_native_host`].
+    /// The stand-in for OS windows, in use after [`Self::with_native_host`].
     #[cfg(feature = "native-windows")]
-    pub host: Option<std::rc::Rc<std::cell::RefCell<NativeHost>>>,
+    host: Option<std::rc::Rc<std::cell::RefCell<NativeHost>>>,
+    #[cfg(feature = "native-windows")]
+    no_host: std::cell::RefCell<NativeHost>,
     style: Option<StyleFn>,
     shapes: Vec<ClippedShape>,
     time: f64,
@@ -74,6 +76,8 @@ impl<P: Clone + Eq + Hash + Debug + Send + Sync + 'static, C: DockContent<P>> Do
             monitors: Vec::new(),
             #[cfg(feature = "native-windows")]
             host: None,
+            #[cfg(feature = "native-windows")]
+            no_host: std::cell::RefCell::new(NativeHost::new(Pos2::ZERO)),
             style: None,
             shapes: Vec::new(),
             time: 0.0,
@@ -158,10 +162,11 @@ impl<P: Clone + Eq + Hash + Debug + Send + Sync + 'static, C: DockContent<P>> Do
         self
     }
 
-    /// The stand-in for OS windows. Panics without [`Self::with_native_host`].
+    /// The stand-in for OS windows: without [`Self::with_native_host`], one with no windows
+    /// that nothing uses.
     #[cfg(feature = "native-windows")]
     pub fn host(&self) -> std::cell::RefMut<'_, NativeHost> {
-        self.host.as_ref().expect("with_native_host").borrow_mut()
+        self.host.as_deref().unwrap_or(&self.no_host).borrow_mut()
     }
 
     /// The viewport of the floating window with this [`super::Floating::id`].

crates/ui/src/docking/trial_tests.rs

@@ -195,7 +195,7 @@ fn localized_covers_every_label_and_contains_takes_a_borrowed_panel() {
     });
     full.textures_delta.clear();
     let values: Vec<&str> = debug.split("_label: \"").skip(1).filter_map(|rest| rest.split('"').next()).collect();
-    assert_eq!(values.len(), 25, "{debug}");
+    assert_eq!(values.len(), 24, "{debug}");
     assert!(values.iter().all(|v| v.starts_with("dock.")), "a label without a key: {values:?}");
     let unique: std::collections::HashSet<_> = values.iter().collect();
     assert_eq!(unique.len(), values.len());