Merge pull request #1450 from Rohilalala/fix/e-route-distance-ten-km

fix(directions): show a 9.96 km route as 10 km, not 10.0 km

changelog.d/1450-directions-ten-km.md

@@ -0,0 +1,3 @@
+- Show a route of 9.95 km or more as 10 km. The Directions row and step
+  cards kept one decimal until the raw distance reached 10 km, so 9.96 km
+  read "10.0 km" (Aditya, @Rohilalala, #1450).

docs/CURRENT-STATE.md

@@ -4317,7 +4317,9 @@ animate). Disable clears all state.
 
 At the metre/kilometre boundary, route distance labels use the rounded
 ten-metre value to select the unit, switching to kilometres at 995 metres;
-a 996-metre leg displays as `1.0 km` rather than `1000 m`.
+a 996-metre leg displays as `1.0 km` rather than `1000 m`. Whole kilometres
+start where the label would round to 10.0 km, so a 9.96 km route displays as
+`10 km` rather than `10.0 km`.
 
 **Keys needed: none.** Directions works on a keyless boot, and the layer is off
 until the operator turns it on.

src/data/directions.test.mjs

@@ -849,6 +849,8 @@ test('route numbers follow the page language and never break from their unit', (
   assert.equal(routeDistanceText(994), '990\u00a0m');
   assert.equal(routeDistanceText(996), '1.0\u00a0km');
   assert.equal(routeDistanceText(1500), '1.5\u00a0km');
+  assert.equal(routeDistanceText(9940), '9.9\u00a0km');
+  assert.equal(routeDistanceText(9960), '10\u00a0km');
   assert.equal(routeDistanceText(2_345_000), '2345\u00a0km');
   assert.equal(routeDurationText(39), '39\u00a0s');
   assert.equal(routeDurationText(59.4), '59\u00a0s');

src/layers/directions/index.js

@@ -113,7 +113,8 @@ export function routeDistanceText(meters) {
   const tens = Math.round(meters / 10) * 10;
   if (tens < 1000) return formatQuantity(tens, 'm');
   const km = meters / 1000;
-  return km < 10
+  // Pick the unit from the tenth it prints: 9.96 km read "10.0 km".
+  return Math.round(meters / 100) < 100
     ? formatQuantity(km, 'km', {
         minimumFractionDigits: 1,
         maximumFractionDigits: 1,