Include popups and tooltips in `Harness::fit_contents` (#7556)

This makes `Harness::fit_contents` also use popups and tooltips to
compute the size of the contents.

crates/egui_kittest/src/lib.rs

@@ -276,14 +276,39 @@ impl<'a, State> Harness<'a, State> {
         self.output = output;
     }
 
+    /// Calculate the rect that includes all popups and tooltips.
+    fn compute_total_rect_with_popups(&self) -> Option<Rect> {
+        // Start with the standard response rect
+        let mut used = if let Some(response) = self.response.as_ref() {
+            response.rect
+        } else {
+            return None;
+        };
+
+        // Add all visible areas from other orders (popups, tooltips, etc.)
+        self.ctx.memory(|mem| {
+            mem.areas()
+                .visible_layer_ids()
+                .into_iter()
+                .filter(|layer_id| layer_id.order != egui::Order::Background)
+                .filter_map(|layer_id| mem.area_rect(layer_id.id))
+                .for_each(|area_rect| used |= area_rect);
+        });
+
+        Some(used)
+    }
+
     /// Resize the test harness to fit the contents. This only works when creating the Harness via
     /// [`Harness::new_ui`] / [`Harness::new_ui_state`] or
     /// [`HarnessBuilder::build_ui`] / [`HarnessBuilder::build_ui_state`].
     pub fn fit_contents(&mut self) {
         self._step(true);
-        if let Some(response) = &self.response {
-            self.set_size(response.rect.size());
+
+        // Calculate size including all content (main UI + popups + tooltips)
+        if let Some(rect) = self.compute_total_rect_with_popups() {
+            self.set_size(rect.size());
         }
+
         self.run_ok();
     }
 

crates/egui_kittest/tests/snapshots/test_tooltip_hidden.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:025942c144891b8862bf931385824e0484e60f4e7766f5d4401511c72ff20756
+size 2975

crates/egui_kittest/tests/snapshots/test_tooltip_shown.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:c267530452adb4f1ed1440df476d576ef4c2d96e6c58068bb57fed4615f5e113
+size 4453

crates/egui_kittest/tests/tests.rs

@@ -16,6 +16,28 @@ fn test_shrink() {
     harness.snapshot("test_shrink");
 }
 
+#[test]
+fn test_tooltip() {
+    let mut harness = Harness::new_ui(|ui| {
+        ui.label("Hello, world!");
+        ui.separator();
+        ui.label("This is a test")
+            .on_hover_text("This\nis\na\nvery\ntall\ntooltip!");
+    });
+
+    harness.fit_contents();
+
+    #[cfg(all(feature = "snapshot", feature = "wgpu"))]
+    harness.snapshot("test_tooltip_hidden");
+
+    harness.get_by_label("This is a test").hover();
+    harness.run_ok();
+    harness.fit_contents();
+
+    #[cfg(all(feature = "snapshot", feature = "wgpu"))]
+    harness.snapshot("test_tooltip_shown");
+}
+
 #[test]
 fn test_modifiers() {
     #[derive(Default)]