Add IME underline, I-beam cursor, and horizontal scroll to Input

crates/core/tests/input.rs

@@ -1,6 +1,7 @@
 use gpui::{
-    Entity, KeyBinding, Modifiers, MouseButton, MouseDownEvent, MouseUpEvent, ParentElement as _,
-    Render, Styled as _, TestAppContext, VisualTestContext, Window, div, point, px,
+    Entity, EntityInputHandler as _, KeyBinding, Modifiers, MouseButton, MouseDownEvent,
+    MouseUpEvent, ParentElement as _, Render, ScrollDelta, ScrollEvent, Styled as _,
+    TestAppContext, VisualTestContext, Window, div, point, px,
 };
 use gpui_native_core::input::{
     INPUT_CONTEXT, Input, InputBindings, InputState, InputStateEvent, Submit, bind_input_keys,
@@ -302,6 +303,50 @@ fn caret_blinks_while_focused_and_holds_solid_while_typing() {
     assert!(!caret_unfocused);
 }
 
+#[test]
+fn horizontal_scroll_follows_the_caret_and_wheels_back() {
+    let text = "a".repeat(300);
+    let (_cx, state, mut visual) = input_window(&text, false);
+    focus(&mut visual, &state);
+    let draw = |visual: &mut VisualTestContext| {
+        visual.update(|window, cx| {
+            window.draw(cx).clear(cx);
+        });
+    };
+
+    // The text index at the field's left edge, through the last paint.
+    let left_edge_index = |visual: &mut VisualTestContext| -> usize {
+        visual
+            .update(|window, cx| {
+                state.update(cx, |state, cx| {
+                    state.character_index_for_point(point(px(2.), px(14.)), window, cx)
+                })
+            })
+            .unwrap_or(0)
+    };
+
+    // The caret starts at the end; the view scrolls to keep it in view, so
+    // the left edge shows a later character.
+    draw(&mut visual);
+    let scrolled_index = left_edge_index(&mut visual);
+    assert!(scrolled_index > 0, "left edge index: {scrolled_index}");
+
+    // Moving to the start scrolls the view back: the left edge is index 0.
+    visual.simulate_keystrokes("home");
+    draw(&mut visual);
+    assert_eq!(left_edge_index(&mut visual), 0);
+
+    // A wheel scroll pans the view right without moving the caret.
+    visual.simulate_event(ScrollEvent {
+        position: point(px(200.), px(20.)),
+        delta: ScrollDelta::Pixels(point(px(-20.), px(0.))),
+        ..Default::default()
+    });
+    draw(&mut visual);
+    let panned_index = left_edge_index(&mut visual);
+    assert!(panned_index > 0, "left edge index: {panned_index}");
+}
+
 #[test]
 fn read_only_blocks_undo_redo_but_set_value_still_writes() {
     let (cx, state, mut visual) = input_window("", false);