fix(maps): avoid 404 on keyless Google tiles-token probe (#1066)

Return an uncached unavailable-token response for keyless Google tile-token requests.

Contribution by @dvilrgamerz.

src/tooling/googleTokenUnavailable.test.mjs

@@ -0,0 +1,94 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createServer } from 'node:http';
+import { once } from 'node:events';
+import { createGoogleTokenSource } from '../maps/googleTokens.js';
+import { googleTokenUnavailablePlugin } from '../../server/standalone/google-token-unavailable.js';
+
+async function withServer({ beforeFallback } = {}, check) {
+  const middlewares = [];
+  const app = {
+    middlewares: {
+      use: (handler) => middlewares.push(handler),
+    },
+  };
+  if (beforeFallback) app.middlewares.use(beforeFallback);
+  googleTokenUnavailablePlugin().configureServer(app);
+  app.middlewares.use((_req, res) => {
+    res.writeHead(404, { 'Content-Type': 'application/json' });
+    res.end(JSON.stringify({ error: 'Unknown API route' }));
+  });
+
+  const server = createServer((req, res) => {
+    let index = 0;
+    const next = () => middlewares[index++]?.(req, res, next);
+    next();
+  });
+  server.listen(0, '127.0.0.1');
+  await once(server, 'listening');
+  const address = server.address();
+  const url = 'http://127.0.0.1:' + address.port;
+  try {
+    await check(url);
+  } finally {
+    server.close();
+    await once(server, 'close');
+  }
+}
+
+test('keyless GET and HEAD return uncached 204 instead of 404', async () => {
+  await withServer({}, async (url) => {
+    for (const method of ['GET', 'HEAD']) {
+      const response = await fetch(url + '/api/google/tiles-token?probe=1', {
+        method,
+      });
+      assert.equal(response.status, 204);
+      assert.equal(response.headers.get('cache-control'), 'no-store');
+      assert.equal(await response.text(), '');
+    }
+  });
+});
+
+test('the existing client treats unavailable tokens as null', async () => {
+  await withServer({}, async (url) => {
+    const source = createGoogleTokenSource({
+      fetchImpl: (path, options) => fetch(new URL(path, url), options),
+    });
+    assert.equal(await source.token(), null);
+  });
+});
+
+test('unrelated API paths and unsupported methods remain 404', async () => {
+  await withServer({}, async (url) => {
+    for (const [path, method] of [
+      ['/api/google/tiles-token/extra', 'GET'],
+      ['/api/not-a-token', 'GET'],
+      ['/api/google/tiles-token', 'POST'],
+    ]) {
+      const response = await fetch(new URL(path, url), { method });
+      assert.equal(response.status, 404);
+    }
+  });
+});
+
+test('a real token provider registered first still wins', async () => {
+  await withServer(
+    {
+      beforeFallback: (req, res, next) => {
+        if (req.url !== '/api/google/tiles-token') return next();
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end(
+          JSON.stringify({
+            accessToken: 'server-token',
+            expiresAt: 10000000000000,
+          }),
+        );
+      },
+    },
+    async (url) => {
+      const response = await fetch(url + '/api/google/tiles-token');
+      assert.equal(response.status, 200);
+      assert.equal((await response.json()).accessToken, 'server-token');
+    },
+  );
+});