test(e2e): unix domain socket (uds/ipc)

test/e2e/unix-domain-socket.spec.ts

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+import { randomUUID } from 'node:crypto';
+import { once } from 'node:events';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import express from 'express';
+import request from 'supertest';
+import { describe, expect, it } from 'vitest';
+
+import { createApp, createProxyMiddleware } from './test-kit.js';
+
+// E2E test of: https://github.com/chimurai/http-proxy-middleware/issues/434#issuecomment-1172896375
+
+describe('E2E Unix Domain Socket proxy (UDS, or IPC sockets)', () => {
+  const startTargetServer = async (socketPath: string) => {
+    const app = express();
+    app.get('/hello', (req, res) => {
+      res.status(200).json({ ok: true });
+    });
+
+    const targetServer = app.listen(socketPath);
+    await once(targetServer, 'listening');
+
+    return {
+      async [Symbol.asyncDispose]() {
+        await new Promise<void>((resolve, reject) => {
+          targetServer.close((error) => (error ? reject(error) : resolve()));
+        });
+      },
+    };
+  };
+
+  const startProxyServer = async (socketPath: string) => {
+    const proxyMiddleware = createProxyMiddleware({
+      target: {
+        socketPath,
+      },
+    });
+
+    const proxyServer = createApp(proxyMiddleware).listen(0);
+    await once(proxyServer, 'listening');
+
+    return {
+      server: proxyServer,
+      async [Symbol.asyncDispose]() {
+        await new Promise<void>((resolve, reject) => {
+          proxyServer.close((error) => (error ? reject(error) : resolve()));
+        });
+      },
+    };
+  };
+
+  it('proxies HTTP request to unix socket target', async () => {
+    // ARRANGE
+    const UNIX_DOMAIN_SOCKET_PATH = join(tmpdir(), `hpm-test-app-${randomUUID()}.sock`);
+
+    await using targetServer = await startTargetServer(UNIX_DOMAIN_SOCKET_PATH);
+    await using proxyServer = await startProxyServer(UNIX_DOMAIN_SOCKET_PATH);
+
+    void targetServer;
+
+    // ACT
+    const response = await request(proxyServer.server).get('/hello').expect(200);
+
+    // ASSERT
+    expect(response.body).toEqual({ ok: true });
+  });
+});