Misc · Numbers: a calculator and a unit converter

misc::Calculator works a typed sum in forms::evaluate's precedence,
from a pad or the keyboard; Enter is equals while the calculator
itself has focus, and Escape clears or passes on. misc::UnitConverter
reads an amount in another unit across seven kinds, with a swap.
Both show numbers through format::significant, which rounds through
Rust's exponent form.

src/misc/tests/numbers.rs

@@ -0,0 +1,126 @@
+use std::cell::Cell;
+
+use gpui::{
+    AnyElement, InteractiveElement, IntoElement, Modifiers, ParentElement, TestAppContext, div,
+};
+
+use super::{press, shown, stage};
+use crate::misc::{Calculator, UnitConverter};
+
+thread_local! {
+    static ESCAPES: Cell<usize> = const { Cell::new(0) };
+}
+
+fn calculator() -> AnyElement {
+    div()
+        .on_key_down(|event, _, _| {
+            if event.keystroke.key == "escape" {
+                ESCAPES.with(|escapes| escapes.set(escapes.get() + 1));
+            }
+        })
+        .child(Calculator::new("calculator"))
+        .into_any_element()
+}
+
+/// Typed keys work the sum in precedence and Enter gives it, but on a focused key Enter presses that key.
+#[gpui::test]
+fn a_calculator_takes_typed_keys(cx: &mut TestAppContext) {
+    let (_, cx) = stage(calculator, cx);
+    press("tab", cx);
+    for key in ["1", "2", "+", "3", "*", "4", "cmd-backspace", "5"] {
+        press(key, cx);
+    }
+    assert!(
+        shown("calculator-12 + 3 × 45", cx),
+        "Command left the delete to the app"
+    );
+    press("backspace", cx);
+    for _ in 0..5 {
+        press("tab", cx);
+    }
+    press("enter", cx);
+    assert!(
+        shown("calculator-12 + 3 × 47", cx),
+        "Enter on the focused 7 typed it"
+    );
+    for _ in 0..5 {
+        press("shift-tab", cx);
+    }
+    press("enter", cx);
+    assert!(
+        shown("calculator-153", cx),
+        "Enter on the calculator is equals"
+    );
+    press("tab", cx);
+    press("enter", cx);
+    press("+", cx);
+    press("5", cx);
+    assert!(
+        shown("calculator-5", cx) && !shown("calculator-153 + 5", cx),
+        "Enter on the focused AC cleared the result"
+    );
+}
+
+/// A press on a key hands the keyboard to the calculator, though the key itself takes no focus.
+#[gpui::test]
+fn a_pressed_key_hands_the_keyboard_to_the_calculator(cx: &mut TestAppContext) {
+    let (_, cx) = stage(calculator, cx);
+    let seven = cx.debug_bounds("key-7").expect("the 7 key").center();
+    cx.simulate_click(seven, Modifiers::none());
+    press("+", cx);
+    press("1", cx);
+    assert!(shown("calculator-7 + 1", cx));
+}
+
+/// Escape clears what there is and stops there; on a blank calculator it passes on, as to a dialog.
+#[gpui::test]
+fn escape_clears_or_passes_on(cx: &mut TestAppContext) {
+    let (_, cx) = stage(calculator, cx);
+    press("tab", cx);
+    press("escape", cx);
+    assert_eq!(ESCAPES.with(Cell::get), 1, "blank, it passed Escape on");
+    press("5", cx);
+    press("escape", cx);
+    press("3", cx);
+    assert!(shown("calculator-3", cx) && !shown("calculator-53", cx));
+    assert_eq!(ESCAPES.with(Cell::get), 1, "clearing kept it");
+}
+
+fn converter() -> AnyElement {
+    UnitConverter::new("converter").into_any_element()
+}
+
+/// A meter reads in feet and, swapped, a foot in meters; another kind starts on its own pair; a typed amount converts, and text that is no number reads as none.
+#[gpui::test]
+fn a_converter_reads_an_amount_in_another_unit(cx: &mut TestAppContext) {
+    let (_, cx) = stage(converter, cx);
+    assert!(shown("converted-3.28084 ft", cx));
+    press("tab", cx);
+    press("tab", cx);
+    press("enter", cx);
+    assert!(shown("converted-0.3048 m", cx), "swapped");
+    press("shift-tab", cx);
+    for key in ["down", "down", "down", "down", "down", "enter"] {
+        press(key, cx);
+    }
+    assert!(
+        shown("converted-33.8 °F", cx),
+        "Temperature starts on Celsius to Fahrenheit"
+    );
+    press("tab", cx);
+    press("tab", cx);
+    press("cmd-a", cx);
+    cx.simulate_input("-40");
+    assert!(shown("converted-−40 °F", cx));
+    press("tab", cx);
+    press("tab", cx);
+    for key in ["down", "down", "enter"] {
+        press(key, cx);
+    }
+    assert!(shown("converted-233.15 K", cx), "picked Kelvin");
+    press("shift-tab", cx);
+    press("shift-tab", cx);
+    press("cmd-a", cx);
+    cx.simulate_input("-");
+    assert!(shown("converted-—", cx));
+}