fix(route): phrase ramp and lane modifiers as directions (#1343)

Correct ramp and lane instructions consistently in server output and localized browser text.

Contribution by @rudycelekli.

src/data/directions.test.mjs

@@ -876,3 +876,46 @@ test('route numbers follow the page language and never break from their unit', (
   const list = directionsStepList({ route });
   assert.equal(list.items[1].lead, '240\u00a0м');
 });
+
+test('ramp and lane wording stays localized after choosing the maneuver form', (t) => {
+  t.after(() => setLocale('en'));
+  const cases = [
+    [
+      'ru',
+      'Въезжайте по съезду плавно налево на I-95',
+      'Сверните на съезд резко направо',
+      'Займите левую полосу',
+    ],
+    [
+      'es',
+      'Toma la rampa ligeramente a la izquierda hacia I-95',
+      'Toma la salida bruscamente a la derecha',
+      'Toma el carril izquierdo',
+    ],
+    [
+      'zh-CN',
+      '向左前方驶入匝道，进入 I-95',
+      '从出口向右后方驶出',
+      '使用左转车道',
+    ],
+  ];
+  for (const [locale, ramp, exit, lane] of cases) {
+    setLocale(locale);
+    assert.equal(
+      directionsInstruction({
+        type: 'on ramp',
+        modifier: 'slight left',
+        name: 'I-95',
+      }),
+      ramp,
+    );
+    assert.equal(
+      directionsInstruction({ type: 'off ramp', modifier: 'sharp right' }),
+      exit,
+    );
+    assert.equal(
+      directionsInstruction({ type: 'use lane', modifier: 'sharp left' }),
+      lane,
+    );
+  }
+});

src/data/routeSteps.js

@@ -54,6 +54,21 @@ function direction(modifier) {
   return DIRECTION_WORDS[key] || key;
 }
 
+/**
+ * "on the left" only fits a bare side. "slight left" is the adverb
+ * "slightly left", and "on the slightly left" is not an instruction.
+ * @param {string} prefix "Take the ramp" or "Take the exit".
+ * @param {string} modifier OSRM maneuver modifier.
+ * @param {string} onto " onto …", or "".
+ */
+function directedWay(prefix, modifier, onto) {
+  const dir = direction(modifier);
+  if (dir === 'left' || dir === 'right')
+    return `${prefix} on the ${dir}${onto}`;
+  if (dir && dir !== 'straight') return `${prefix} ${dir}${onto}`;
+  return `${prefix}${onto}`;
+}
+
 function ordinal(n) {
   if (!Number.isInteger(n) || n < 1) return null;
   const suffix =
@@ -103,13 +118,9 @@ export function instructionFor(step) {
     case 'merge':
       return dir ? `Merge ${dir}${onto}` : `Merge${onto}`;
     case 'on ramp':
-      return dir
-        ? `Take the ramp on the ${dir}${onto}`
-        : `Take the ramp${onto}`;
+      return directedWay('Take the ramp', modifier, onto);
     case 'off ramp':
-      return dir
-        ? `Take the exit on the ${dir}${onto}`
-        : `Take the exit${onto}`;
+      return directedWay('Take the exit', modifier, onto);
     case 'roundabout':
     case 'rotary': {
       const exit = ordinal(step?.exit);
@@ -124,8 +135,14 @@ export function instructionFor(step) {
     case 'exit roundabout':
     case 'exit rotary':
       return `Exit the roundabout${onto}`;
-    case 'use lane':
-      return dir ? `Use the ${dir} lane${onto}` : `Continue${onto}`;
+    case 'use lane': {
+      const lane = modifier.includes('left')
+        ? 'left'
+        : modifier.includes('right')
+          ? 'right'
+          : '';
+      return lane ? `Use the ${lane} lane${onto}` : `Continue${onto}`;
+    }
     case 'notification':
     default:
       return `Continue${onto}`;

src/data/routeSteps.test.mjs

@@ -77,6 +77,26 @@ test('instructions read like a navigator, one sentence per OSRM maneuver', () =>
     instructionFor({ type: 'on ramp', modifier: 'left' }),
     'Take the ramp on the left',
   );
+  assert.equal(
+    instructionFor({ type: 'on ramp', modifier: 'slight left', name: 'I-95' }),
+    'Take the ramp slightly left onto I-95',
+  );
+  assert.equal(
+    instructionFor({ type: 'off ramp', modifier: 'sharp right', ref: 'I-280' }),
+    'Take the exit sharply right onto I-280',
+  );
+  assert.equal(
+    instructionFor({ type: 'on ramp', modifier: 'straight', name: 'US 101' }),
+    'Take the ramp onto US 101',
+  );
+  assert.equal(
+    instructionFor({ type: 'use lane', modifier: 'slight left' }),
+    'Use the left lane',
+  );
+  assert.equal(
+    instructionFor({ type: 'use lane', modifier: 'right', name: 'Main St' }),
+    'Use the right lane onto Main St',
+  );
   assert.equal(
     instructionFor({
       type: 'merge',