feat(layers): add FAA drone restrictions airspace layer

Show US prohibited and restricted special-use airspace from the keyless
FAA SUA FeatureServer as an off-by-default Infrastructure layer, with
share-link token 3 and an informational-only disclaimer.

src/layers/droneAirspace/source.test.mjs

@@ -0,0 +1,105 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createDroneAirspaceSource } from './source.js';
+import { normalizeDroneAirspaceSnapshot } from './records.js';
+import { droneAirspaceProxy } from '../../../server/providers/droneAirspace.js';
+
+const ring = [
+  [-77.04, 38.89],
+  [-77.03, 38.89],
+  [-77.03, 38.9],
+  [-77.04, 38.89],
+];
+const validPayload = {
+  features: [
+    {
+      id: 310,
+      geometry: { type: 'Polygon', coordinates: [ring] },
+      properties: {
+        NAME: 'P-56',
+        TYPE_CODE: 'P',
+        OBJECTID: 310,
+      },
+    },
+  ],
+};
+
+test('a successful response yields normalized zone rows', async () => {
+  let requested;
+  const source = createDroneAirspaceSource({
+    fetchImpl: async (url) => {
+      requested = String(url);
+      return Response.json({
+        rows: normalizeDroneAirspaceSnapshot(validPayload),
+      });
+    },
+  });
+  const rows = await source.getSnapshot();
+  assert.equal(rows.length, 1);
+  assert.equal(rows[0].stableId, '310');
+  assert.equal(requested, '/api/drone-airspace');
+});
+
+test('a truncated response pages until the feed is complete', async () => {
+  const pageRing = (id) => ({
+    id,
+    geometry: { type: 'Polygon', coordinates: [ring] },
+    properties: { NAME: `P-${id}`, TYPE_CODE: 'P', OBJECTID: id },
+  });
+  const requests = [];
+  let handler;
+  const plugin = droneAirspaceProxy({
+    fetchImpl: async (url) => {
+      requests.push(new URL(String(url)).searchParams.get('resultOffset'));
+      const page = requests.length;
+      return Response.json({
+        features: [pageRing(page)],
+        properties: { exceededTransferLimit: page < 3 },
+      });
+    },
+  });
+  plugin.configureServer({
+    middlewares: {
+      use: (_path, callback) => {
+        handler = callback;
+      },
+    },
+  });
+  let payload;
+  await handler(
+    { url: '/', method: 'GET' },
+    {
+      writeHead(status) {
+        assert.equal(status, 200);
+      },
+      end(body) {
+        payload = JSON.parse(body);
+      },
+    },
+  );
+  const rows = payload.rows;
+  assert.deepEqual(
+    rows.map((row) => row.stableId),
+    ['1', '2', '3'],
+  );
+  assert.deepEqual(requests, [null, '1', '2']);
+});
+
+test('an upstream failure surfaces its HTTP status', async () => {
+  const source = createDroneAirspaceSource({
+    fetchImpl: async () => ({ ok: false, status: 503 }),
+  });
+  await assert.rejects(source.getSnapshot(), /FAA SUA HTTP 503/);
+});
+
+test('a malformed successful response is never accepted as an empty snapshot', async () => {
+  for (const payload of [{}, { rows: null }, { rows: {} }]) {
+    const source = createDroneAirspaceSource({
+      fetchImpl: async () => Response.json(payload),
+    });
+    await assert.rejects(
+      source.getSnapshot(),
+      /Malformed drone airspace snapshot/,
+    );
+  }
+});