From 303d98c7ca09908b557bdd8d8691ca609a4f389f Mon Sep 17 00:00:00 2001
From: Lawrence Forooghian <lawrence@forooghian.com>
Date: Tue, 30 Jul 2024 09:20:47 +0100
Subject: [PATCH 1/3] Fix logging of test web server port

---
 test/web_server.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/web_server.js b/test/web_server.js
index 9d10abcb3..1660dc6c2 100755
--- a/test/web_server.js
+++ b/test/web_server.js
@@ -48,7 +48,7 @@ class MochaServer {
     const port = process.env.PORT || 3000;
     this.server = app.listen(port);
 
-    console.log('Mocha test server listening on http://localhost:3000/');
+    console.log(`Mocha test server listening on http://localhost:${port}/`);
   }
 
   close() {

From 33e66514d7e2e062a5a901eff0f69f8de198d959 Mon Sep 17 00:00:00 2001
From: Lawrence Forooghian <lawrence@forooghian.com>
Date: Tue, 30 Jul 2024 09:22:46 +0100
Subject: [PATCH 2/3] Handle errors when starting test web server

The following errors were just being absorbed, making them hard to
notice and debug:

- app.listen throwing a synchronous error (e.g. in the case where you
  specify -1 as a port number)

- app.listen throwing an asynchronous error (e.g. in the EADDRINUSE
  case)
---
 test/support/runPlaywrightTests.js | 2 +-
 test/web_server.js                 | 7 +++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/test/support/runPlaywrightTests.js b/test/support/runPlaywrightTests.js
index be73457d7..edbcc1531 100644
--- a/test/support/runPlaywrightTests.js
+++ b/test/support/runPlaywrightTests.js
@@ -10,7 +10,7 @@ const playwrightBrowsers = ['chromium', 'firefox', 'webkit'];
 const mochaServer = new MochaServer(/* playwrightTest: */ true);
 
 const runTests = async (browserType) => {
-  mochaServer.listen();
+  await mochaServer.listen();
   const browser = await browserType.launch();
   const context = await browser.newContext();
   const page = await context.newPage();
diff --git a/test/web_server.js b/test/web_server.js
index 1660dc6c2..7b510bee3 100755
--- a/test/web_server.js
+++ b/test/web_server.js
@@ -46,13 +46,16 @@ class MochaServer {
     app.use(express.static(__dirname));
 
     const port = process.env.PORT || 3000;
-    this.server = app.listen(port);
+    await new Promise((resolve, reject) => {
+      this.server = app.listen(port, resolve);
+      this.server.once('error', reject);
+    });
 
     console.log(`Mocha test server listening on http://localhost:${port}/`);
   }
 
   close() {
-    this.server.close();
+    this.server?.close();
   }
 }
 

From 3ce70325c6e6c511012d73ecce52a2483bfe18b3 Mon Sep 17 00:00:00 2001
From: Lawrence Forooghian <lawrence@forooghian.com>
Date: Tue, 30 Jul 2024 09:45:32 +0100
Subject: [PATCH 3/3] Fail test web server if port is unavailable for IPv4

---
 test/web_server.js | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/test/web_server.js b/test/web_server.js
index 7b510bee3..1e6822fde 100755
--- a/test/web_server.js
+++ b/test/web_server.js
@@ -13,6 +13,8 @@ var express = require('express'),
  */
 
 class MochaServer {
+  servers = [];
+
   constructor(playwrightTest) {
     this.playwrightTest = playwrightTest;
   }
@@ -46,16 +48,28 @@ class MochaServer {
     app.use(express.static(__dirname));
 
     const port = process.env.PORT || 3000;
-    await new Promise((resolve, reject) => {
-      this.server = app.listen(port, resolve);
-      this.server.once('error', reject);
-    });
+    // Explicitly listen on the IPv4 and IPv6 loopback interfaces. If you don’t
+    // pass an address to `app.listen`, then it will bind in a manner that
+    // succeeds even if the IPv4 socket address is already in use, as long as
+    // the IPv6 socket address is free. This can lead to confusion.
+    await this.startServer(app, '127.0.0.1', port);
+    await this.startServer(app, '::1', port);
 
     console.log(`Mocha test server listening on http://localhost:${port}/`);
   }
 
+  async startServer(app, address, port) {
+    await new Promise((resolve, reject) => {
+      const server = app.listen(port, address, resolve);
+      this.servers.push(server);
+      server.once('error', reject);
+    });
+  }
+
   close() {
-    this.server?.close();
+    for (const server of this.servers) {
+      server.close();
+    }
   }
 }