Misc · Time: Lap turns Reset, laps and tickers tested

The stopwatch's second button reads Lap while running and Reset once
paused, on one focus handle, and Reset hands focus to Start, so no
press leaves focus stranded. Lap rows carry selectors; tests hold
their order and times, count the tickers' wakes, and a WorldClock
without places fails.

src/misc/stopwatch.rs

@@ -1,8 +1,8 @@
 use std::time::{Duration, Instant};
 
 use gpui::{
-    App, ElementId, InteractiveElement, IntoElement, ParentElement, RenderOnce, Styled, Task,
-    Window, div,
+    App, ElementId, FocusHandle, InteractiveElement, IntoElement, ParentElement, RenderOnce,
+    Styled, Task, Window, div,
 };
 
 use crate::{
@@ -69,7 +69,7 @@ pub(crate) fn tenths(elapsed: Duration) -> String {
     }
 }
 
-/// Time that runs while started and holds while paused, in tenths, with Start or Pause, Lap and Reset under it and the laps below, newest first: each lap's own time and the total at its end. It reads the executor's clock.
+/// Time that runs while started and holds while paused, in tenths, with Start or Pause under it beside Lap, which reads Reset once paused, and the laps below, newest first: each lap's own time and the total at its end. It reads the executor's clock.
 #[derive(IntoElement)]
 pub struct Stopwatch {
     id: ElementId,
@@ -87,7 +87,14 @@ impl RenderOnce for Stopwatch {
         let run = window.use_keyed_state((id.clone(), "run"), cx, |_, _| Run::default());
         let toggle = tab_stop((id.clone(), "toggle").into(), true, window, cx);
         let now = cx.background_executor().now();
-        if run.read(cx).since.is_some() && run.read(cx).tick.is_none() {
+        let (running, elapsed) = (run.read(cx).since.is_some(), run.read(cx).elapsed(now));
+        let side = tab_stop(
+            (id.clone(), "side").into(),
+            running || !elapsed.is_zero(),
+            window,
+            cx,
+        );
+        if running && run.read(cx).tick.is_none() {
             let (view, weak) = (window.current_view(), run.downgrade());
             let task = window.spawn(cx, async move |cx| {
                 loop {
@@ -103,26 +110,28 @@ impl RenderOnce for Stopwatch {
             });
             run.update(cx, |run, _| run.tick = Some(task));
         }
-        let (running, elapsed, laps) = {
-            let run = run.read(cx);
-            (run.since.is_some(), run.elapsed(now), run.laps.clone())
-        };
+        let laps = run.read(cx).laps.clone();
         let theme = cx.theme();
         let shown = tenths(elapsed);
-        let act = |name: &'static str, edit: fn(&mut Run, Instant)| {
-            let run = run.clone();
-            move |_: &gpui::ClickEvent, _: &mut Window, cx: &mut App| {
+        let act = |name: &'static str, edit: fn(&mut Run, Instant), then: Option<&FocusHandle>| {
+            let (run, then) = (run.clone(), then.cloned());
+            move |_: &gpui::ClickEvent, window: &mut Window, cx: &mut App| {
                 let now = cx.background_executor().now();
                 run.update(cx, |run, cx| {
                     edit(run, now);
                     log::info!("stopwatch: {name} at {}", tenths(run.elapsed(now)));
                     cx.notify();
                 });
+                if let Some(then) = &then {
+                    window.focus(then);
+                }
             }
         };
         let rows = laps.iter().enumerate().rev().map(|(ix, total)| {
             let before = ix.checked_sub(1).map_or(Duration::ZERO, |last| laps[last]);
+            let own = tenths(*total - before);
             div()
+                .debug_selector(|| format!("lap-{}-{own}-{}", ix + 1, tenths(*total)))
                 .flex()
                 .gap_3()
                 .py_1()
@@ -134,7 +143,7 @@ impl RenderOnce for Stopwatch {
                     tabular(div())
                         .flex_none()
                         .text_color(theme.colors.fg)
-                        .child(tenths(*total - before)),
+                        .child(own.clone()),
                 )
                 .child(tabular(div()).flex_none().child(tenths(*total)))
         });
@@ -166,19 +175,25 @@ impl RenderOnce for Stopwatch {
                         })
                         .focus_handle(&toggle)
                         .on_click(match running {
-                            true => act("pause", Run::pause),
-                            false => act("start", Run::start),
+                            true => act("pause", Run::pause, None),
+                            false => act("start", Run::start, None),
                         }),
                     )
                     .child(
-                        Button::new((id.clone(), "lap"), "Lap")
-                            .disabled(!running)
-                            .on_click(act("lap", Run::lap)),
-                    )
-                    .child(
-                        Button::new((id.clone(), "reset"), "Reset")
-                            .disabled(running || elapsed.is_zero())
-                            .on_click(act("reset", |run, _| run.reset())),
+                        Button::new(
+                            (id.clone(), "side"),
+                            if running || elapsed.is_zero() {
+                                "Lap"
+                            } else {
+                                "Reset"
+                            },
+                        )
+                        .focus_handle(&side)
+                        .disabled(!running && elapsed.is_zero())
+                        .on_click(match running {
+                            true => act("lap", Run::lap, None),
+                            false => act("reset", |run, _| run.reset(), Some(&toggle)),
+                        }),
                     ),
             )
             .child(div().flex().flex_col().children(rows))