refactor: persist mileage drill context in URL

src/modules/mileage/drill-context.test.ts

@@ -0,0 +1,53 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { buildMileageDrillUrl, parseMileageDrillContext } from './drill-context.js';
+
+test('parses a vehicle drill context', () => {
+  const context = parseMileageDrillContext(
+    '?mileageLevel=vehicle&mileagePlate=%E7%B2%A4A08190F&mileageStart=2026-08-01&mileageEnd=2026-08-07&mileageSource=instrument,gps',
+  );
+
+  assert.deepEqual(context, {
+    level: 'vehicle',
+    plate: '粤A08190F',
+    startDate: '2026-08-01',
+    endDate: '2026-08-07',
+    sourcePriority: ['instrument', 'gps'],
+  });
+});
+
+test('requires complete context for breakdown and vehicle levels', () => {
+  assert.equal(parseMileageDrillContext('?mileageLevel=vehicle').level, 'overview');
+  assert.equal(parseMileageDrillContext('?mileageLevel=breakdown&mileageDimension=region').level, 'overview');
+});
+
+test('builds a namespaced URL and preserves unrelated parameters', () => {
+  const url = buildMileageDrillUrl(
+    { pathname: '/asset', search: '?company=5&legacy=1', hash: '#mileage' },
+    {
+      level: 'vehicle',
+      plate: '粤A08190F',
+      startDate: '2026-08-01',
+      endDate: '2026-08-07',
+      sourcePriority: ['instrument'],
+    },
+  );
+
+  assert.equal(
+    url,
+    '/asset?company=5&legacy=1&mileageLevel=vehicle&mileagePlate=%E7%B2%A4A08190F&mileageStart=2026-08-01&mileageEnd=2026-08-07&mileageSource=instrument#mileage',
+  );
+});
+
+test('clears entity drill parameters when returning to overview', () => {
+  const url = buildMileageDrillUrl(
+    {
+      pathname: '/asset',
+      search: '?mileageLevel=vehicle&mileagePlate=%E7%B2%A4A08190F&company=5',
+      hash: '#mileage',
+    },
+    { level: 'overview', sourcePriority: ['instrument'] },
+  );
+
+  assert.equal(url, '/asset?company=5&mileageSource=instrument#mileage');
+});