add select component built on menu

crates/core/tests/select_pointer.rs

@@ -0,0 +1,98 @@
+use std::{cell::RefCell, rc::Rc};
+
+use gpui::{
+    Context, IntoElement, MouseButton, ParentElement as _, Render, Styled as _, TestAppContext,
+    VisualTestContext, Window, div, point, px,
+};
+use gpui_native_core::select::Select;
+use gpui_native_theme::Theme;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum Level {
+    Low,
+    Mid,
+    High,
+}
+
+const LEVELS: [(Level, &str); 3] = [
+    (Level::Low, "Low"),
+    (Level::Mid, "Mid"),
+    (Level::High, "High"),
+];
+
+type Changes = Rc<RefCell<Vec<Option<Level>>>>;
+
+struct Harness {
+    value: Option<Level>,
+    changes: Changes,
+}
+
+impl Render for Harness {
+    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let changes = self.changes.clone();
+        let view = cx.entity();
+        div().size_full().p_4().child(
+            Select::new("level")
+                .options(LEVELS)
+                .selected(self.value)
+                .on_change(move |next, _window, cx| {
+                    changes.borrow_mut().push(next);
+                    view.update(cx, |harness, cx| {
+                        harness.value = next;
+                        cx.notify();
+                    });
+                }),
+        )
+    }
+}
+
+fn level_window() -> (TestAppContext, VisualTestContext, Changes) {
+    let mut cx = TestAppContext::single();
+    cx.update(Theme::init);
+    let changes = Rc::new(RefCell::new(Vec::new()));
+    let harness_changes = changes.clone();
+    let window = cx.add_window(move |_, _| Harness {
+        value: None,
+        changes: harness_changes,
+    });
+    let mut visual = VisualTestContext::from_window(window.into(), &cx);
+    visual.update(|window, cx| {
+        window.draw(cx).clear(cx);
+    });
+    (cx, visual, changes)
+}
+
+fn click(visual: &mut VisualTestContext, position: gpui::Point<gpui::Pixels>) {
+    visual.simulate_mouse_down(position, MouseButton::Left, gpui::Modifiers::default());
+    visual.simulate_mouse_up(position, MouseButton::Left, gpui::Modifiers::default());
+}
+
+/// The trigger band is `16..46`; the panel hangs 4 px below it with a 4 px
+/// inner padding, so the three rows ride `~58..90`, `~90..122`, `~122..154`.
+/// Every option must answer a pointer press — a popup that clips its last
+/// item never does.
+#[test]
+fn every_option_row_answers_the_pointer() {
+    let (_cx, mut visual, changes) = level_window();
+
+    let expected = [
+        (px(74.), Level::Low),
+        (px(106.), Level::Mid),
+        (px(138.), Level::High),
+    ];
+    for (y, value) in expected {
+        click(&mut visual, point(px(100.), px(31.)));
+        visual.update(|window, cx| {
+            window.draw(cx).clear(cx);
+        });
+        click(&mut visual, point(px(100.), y));
+        visual.update(|window, cx| {
+            window.draw(cx).clear(cx);
+        });
+        assert_eq!(
+            changes.borrow().last(),
+            Some(&Some(value)),
+            "pressing {value:?}'s row must choose it"
+        );
+    }
+}