test: bind route test servers to the loopback address they request

tests/server/routes/compiler.routes.test.ts

@@ -35,7 +35,7 @@ function createApp() {
 /** Start the express app on a random port and return base URL + close fn */
 function listen(app: express.Express): Promise<{ baseUrl: string; server: http.Server }> {
   return new Promise((resolve) => {
-    const server = app.listen(0, () => {
+    const server = app.listen(0, "127.0.0.1", () => {
       const addr = server.address() as { port: number };
       resolve({ baseUrl: `http://127.0.0.1:${addr.port}`, server });
     });

tests/server/routes/examples.routes.test.ts

@@ -60,7 +60,7 @@ describe("request-scoped examples routes", () => {
       validateRateLimiter: new IdentityRateLimiter("test validate", { maxRequests: validateMax, windowMs: 60_000, blockDurationMs: 60_000 }),
       overrideRateLimiter: new IdentityRateLimiter("test override", { maxRequests: overrideMax, windowMs: 60_000, blockDurationMs: 30_000 }),
     });
-    server = app.listen(0);
+    server = app.listen(0, "127.0.0.1");
     await new Promise<void>((resolve) => server!.once("listening", resolve));
     const address = server.address() as { port: number };
     return { baseUrl: `http://127.0.0.1:${address.port}`, validate, getCatalog, getExample };

tests/server/routes/routes-core.test.ts

@@ -65,7 +65,7 @@ vi.mock("../../../server/services/examples/examples-repository", () => ({
 
 function listen(app: express.Express): Promise<{ baseUrl: string; server: http.Server }> {
   return new Promise((resolve) => {
-    const server = app.listen(0, () => {
+    const server = app.listen(0, "127.0.0.1", () => {
       const address = server.address() as { port: number };
       resolve({ baseUrl: `http://127.0.0.1:${address.port}`, server });
     });

tests/server/routes/server-status.test.ts

@@ -48,7 +48,7 @@ vi.mock("../../../server/services/sandbox/docker-compile-semaphore", () => ({
 
 function listen(app: express.Express): Promise<{ baseUrl: string; server: http.Server }> {
   return new Promise((resolve) => {
-    const server = app.listen(0, () => {
+    const server = app.listen(0, "127.0.0.1", () => {
       const addr = server.address() as { port: number };
       resolve({ baseUrl: `http://127.0.0.1:${addr.port}`, server });
     });

tests/server/routes/test-reset.routes.test.ts

@@ -32,7 +32,7 @@ async function postToReset(isTest: boolean, enabled: boolean) {
   });
 
   const server = await new Promise<http.Server>((resolve) => {
-    const listeningServer = app.listen(0, () => resolve(listeningServer));
+    const listeningServer = app.listen(0, "127.0.0.1", () => resolve(listeningServer));
   });
   servers.push(server);
   const address = server.address();

tests/server/routes/tutor.routes.test.ts

@@ -10,7 +10,7 @@ import { TutorService } from "../../../server/services/tutor/tutor-service";
 
 function listen(app: express.Express): Promise<{ url: string; server: http.Server }> {
   return new Promise((resolve) => {
-    const server = app.listen(0, () => {
+    const server = app.listen(0, "127.0.0.1", () => {
       const address = server.address() as { port: number };
       resolve({ url: `http://127.0.0.1:${address.port}`, server });
     });

tests/server/services/protocol-version.test.ts

@@ -27,7 +27,7 @@ describe("protocol version contract", () => {
     app.use("/api", apiVersionMiddleware);
     app.get("/api/status", (_req, res) => res.json({ status: "ok" }));
     const server = createServer(app);
-    await new Promise<void>((resolve) => server.listen(0, resolve));
+    await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
     const address = server.address();
     const port = typeof address === "object" && address ? address.port : 0;
     const response = await fetch(`http://127.0.0.1:${port}/api/status`, {