From 6e11db09dda7d093bf0b8f6f8c1e8672185767c5 Mon Sep 17 00:00:00 2001
From: Yagiz Nizipli <yagiz@nizipli.com>
Date: Tue, 8 Oct 2024 10:09:34 -0400
Subject: [PATCH] add node:sys to comply with nodejs_compat

---
 src/workerd/api/node/BUILD.bazel              |  6 +++++
 src/workerd/api/node/module.c++               | 10 +++++++
 src/workerd/api/node/tests/sys-nodejs-test.js | 27 +++++++++++++++++++
 .../api/node/tests/sys-nodejs-test.wd-test    | 15 +++++++++++
 4 files changed, 58 insertions(+)
 create mode 100644 src/workerd/api/node/tests/sys-nodejs-test.js
 create mode 100644 src/workerd/api/node/tests/sys-nodejs-test.wd-test

diff --git a/src/workerd/api/node/BUILD.bazel b/src/workerd/api/node/BUILD.bazel
index e4818bf06ce..33aa9c94706 100644
--- a/src/workerd/api/node/BUILD.bazel
+++ b/src/workerd/api/node/BUILD.bazel
@@ -189,6 +189,12 @@ wd_test(
     data = ["tests/util-nodejs-test.js"],
 )
 
+wd_test(
+    src = "tests/sys-nodejs-test.wd-test",
+    args = ["--experimental"],
+    data = ["tests/sys-nodejs-test.js"],
+)
+
 wd_test(
     size = "large",
     src = "tests/zlib-nodejs-test.wd-test",
diff --git a/src/workerd/api/node/module.c++ b/src/workerd/api/node/module.c++
index 16c4fbfd697..b028f71c421 100644
--- a/src/workerd/api/node/module.c++
+++ b/src/workerd/api/node/module.c++
@@ -61,6 +61,16 @@ jsg::JsValue ModuleUtil::createRequire(jsg::Lock& js, kj::String path) {
       // If the specifier begins with one of our known prefixes, let's not resolve
       // it against the referrer.
       try {
+        if (spec == "node:sys" || spec == "sys") [[unlikely]] {
+          // The sys module was renamed to 'util'. This shim remains to keep old programs
+          // working. `sys` is deprecated and shouldn't be used.
+
+          // Note to maintainers: Although this module has been deprecated for a while
+          // Node.js do not plan to remove it.
+          // See: https://github.com/nodejs/node/pull/35407#issuecomment-700693439
+          return kj::Path::parse("node:util");
+        }
+
         if (spec.startsWith("node:") || spec.startsWith("cloudflare:") ||
             spec.startsWith("workerd:")) {
           return kj::Path::parse(spec);
diff --git a/src/workerd/api/node/tests/sys-nodejs-test.js b/src/workerd/api/node/tests/sys-nodejs-test.js
new file mode 100644
index 00000000000..59d354ae6ac
--- /dev/null
+++ b/src/workerd/api/node/tests/sys-nodejs-test.js
@@ -0,0 +1,27 @@
+import assert from 'node:assert';
+import module from 'node:module';
+
+export const getBuiltinModule = {
+  async test() {
+    assert.deepStrictEqual(
+      process.getBuiltinModule('node:sys'),
+      process.getBuiltinModule('node:util')
+    );
+  },
+};
+
+export const canBeRequired = {
+  async test() {
+    const require = module.createRequire('/hello');
+    assert.deepStrictEqual(require('node:sys'), require('node:util'));
+    assert.deepStrictEqual(require('sys'), require('node:util'));
+  },
+};
+
+export const canBeImported = {
+  async test() {
+    const sys = await import('node:sys');
+    const util = await import('node:util');
+    assert.deepStrictEqual(sys, util);
+  },
+};
diff --git a/src/workerd/api/node/tests/sys-nodejs-test.wd-test b/src/workerd/api/node/tests/sys-nodejs-test.wd-test
new file mode 100644
index 00000000000..3f34cd64fc2
--- /dev/null
+++ b/src/workerd/api/node/tests/sys-nodejs-test.wd-test
@@ -0,0 +1,15 @@
+using Workerd = import "/workerd/workerd.capnp";
+
+const unitTests :Workerd.Config = (
+  services = [
+    ( name = "nodejs-sys-test",
+      worker = (
+        modules = [
+          (name = "worker", esModule = embed "sys-nodejs-test.js")
+        ],
+        compatibilityDate = "2023-10-01",
+        compatibilityFlags = ["nodejs_compat_v2"],
+      )
+    ),
+  ],
+);