test(producer): unit tests never reach the network (#5135)

* test(producer): unit tests never reach the network

* test(producer): the unit lane refuses sockets to other hosts, not only fetch

* test(producer): refuse outside hosts at the lookup, not by parsing socket calls

* test(producer): keep dns.lookup promisify-compatible under the no-network guard

packages/producer/scripts/no-network.mjs

@@ -0,0 +1,16 @@
+import dns from "node:dns";
+
+// Unit tests run offline: fetch throws, and a lookup of any host but this machine fails, which also covers a test
+// environment's own fetch (happy-dom's) and node:http. A test that needs a response stubs fetch itself.
+const LOCAL = new Set(["localhost"]);
+const refusal = (target) => new TypeError(`No network in unit tests: ${target}`);
+
+globalThis.fetch = async (input) => {
+  throw refusal(input?.url ?? input);
+};
+
+const { lookup } = dns;
+const guarded = (host, ...rest) =>
+  LOCAL.has(host) ? lookup(host, ...rest) : process.nextTick(rest.at(-1), refusal(host));
+// Keeps the original's own properties, among them what util.promisify reads to resolve { address, family }.
+dns.lookup = Object.defineProperties(guarded, Object.getOwnPropertyDescriptors(lookup));

packages/producer/scripts/run-test-lane.mjs

@@ -1,4 +1,5 @@
 import { spawnSync } from "node:child_process";
+import { fileURLToPath } from "node:url";
 import { discoverProducerTests, PRODUCER_ROOT } from "./test-classification.mjs";
 
 const lane = process.argv[2];
@@ -14,10 +15,13 @@ const tests = discoverProducerTests().filter(
   (test) => test.lane === lane && (!requestedRunner || test.runner === requestedRunner),
 );
 
-function run(args) {
+const noNetwork = new URL("./no-network.mjs", import.meta.url);
+const unit = lane === "unit";
+
+function run(args, env = {}) {
   const result = spawnSync("bun", args, {
     cwd: PRODUCER_ROOT,
-    env: { ...process.env, HYPERFRAMES_TEST_LANE: lane },
+    env: { ...process.env, HYPERFRAMES_TEST_LANE: lane, ...env },
     stdio: "inherit",
   });
   if (result.error) throw result.error;
@@ -25,10 +29,13 @@ function run(args) {
 }
 
 const vitestFiles = tests.filter((test) => test.runner === "vitest").map((test) => test.file);
-if (vitestFiles.length > 0) run(["x", "vitest", "run", ...vitestFiles]);
+const vitestEnv = unit
+  ? { NODE_OPTIONS: `${process.env.NODE_OPTIONS ?? ""} --import ${noNetwork.href}`.trim() }
+  : {};
+if (vitestFiles.length > 0) run(["x", "vitest", "run", ...vitestFiles], vitestEnv);
 
 // Bun's mock.module registry is process-global. Run each file in a fresh
 // process so mocks from one source test cannot mutate another test's imports.
 for (const test of tests.filter((entry) => entry.runner === "bun")) {
-  run(["test", test.file]);
+  run(["test", ...(unit ? ["--preload", fileURLToPath(noNetwork)] : []), test.file]);
 }

packages/producer/src/noNetwork.test.ts

@@ -0,0 +1,6 @@
+import { expect, it } from "bun:test";
+
+// scripts/run-test-lane.mjs preloads scripts/no-network.mjs for the unit lane.
+it("reaches no network in the unit lane", async () => {
+  await expect(fetch("https://example.com")).rejects.toThrow("No network in unit tests");
+});

packages/producer/src/noNetworkNode.test.ts

@@ -0,0 +1,15 @@
+// @vitest-environment happy-dom
+import { get } from "node:http";
+import { expect, it } from "vitest";
+
+// scripts/run-test-lane.mjs imports scripts/no-network.mjs into the unit lane's vitest workers.
+it("refuses happy-dom's own fetch in the unit lane", async () => {
+  await expect(fetch("https://example.com")).rejects.toThrow("No network in unit tests");
+});
+
+it("refuses a node:http request to another host in the unit lane", async () => {
+  const request = new Promise((resolve, reject) => {
+    get("http://example.com", resolve).on("error", reject);
+  });
+  await expect(request).rejects.toThrow("No network in unit tests");
+});

packages/producer/src/services/htmlCompiler.test.ts

@@ -1686,7 +1686,7 @@ describe("crossorigin attribute stripping", () => {
 //
 // Tests run on localizeRemoteMediaSources directly (exported for testing) to
 // avoid invoking ffprobe / the full compileForRender pipeline. fetch is patched
-// in-process for success cases; real 404s from example.com cover fallback.
+// in-process for success cases; the unit lane's refused network covers fallback.
 
 describe("localizeRemoteMediaSources", () => {
   it("rewrites remote <video> src to _remote_media path when download succeeds", async () => {

scripts/test-reachability.json

@@ -60,7 +60,7 @@
         "packages/producer/tests/**/*.test.ts"
       ],
       "sources": {
-        "packages/producer/scripts/run-test-lane.mjs": "bff02680f19eebcce0df72cdeedbbc05edfdcede3f3f60658fc0cb18ed8c59f6",
+        "packages/producer/scripts/run-test-lane.mjs": "638885e14480d03290803389325a655f3749442167d784e07bb3af3404598af7",
         "packages/producer/scripts/test-classification.mjs": "ae0cd9e09bf93df932d41649855f86ebb2230b25aabf3e56355fed8f101a0322",
         ".github/workflows/ci.yml#job#producer-source-tests": "45da72aa6cf08cdfd5bcf5311e89f12af4842f9eebc6735df19da8c02f4d4864",
         "packages/producer/package.json#script#test:unit": "ae6beda8319d166774be958ea5593cd27dbf7f6c9bce1d787a3fe28dfc3477b1",