doc,test: add documentation and test on how to use addons in SEA

doc/api/single-executable-applications.md

@@ -421,6 +421,38 @@ are equal to [`process.execPath`][].
 The value of `__dirname` in the injected main script is equal to the directory
 name of [`process.execPath`][].
 
+### Using native addons in the injected main script
+
+Native addons can be bundled as assets into the single-executable application
+by specifying them in the `assets` field of the configuration file used to
+generate the single-executable application preparation blob.
+The addon can then be loaded in the injected main script by writing the asset
+to a temporary file and loading it with `process.dlopen()`.
+
+```json
+{
+  "main": "/path/to/bundled/script.js",
+  "output": "/path/to/write/the/generated/blob.blob",
+  "assets": {
+    "myaddon.node": "/path/to/myaddon/build/Release/myaddon.node"
+  }
+}
+```
+
+```js
+// script.js
+const fs = require('node:fs');
+const os = require('node:os');
+const path = require('node:path');
+const { getRawAsset } = require('node:sea');
+const addonPath = path.join(os.tmpdir(), 'myaddon.node');
+fs.writeFileSync(addonPath, new Uint8Array(getRawAsset('myaddon.node')));
+const myaddon = { exports: {} };
+process.dlopen(myaddon, addonPath);
+console.log(myaddon.exports);
+fs.rmSync(addonPath);
+```
+
 ## Notes
 
 ### Single executable application creation process

test/node-api/node-api.status

@@ -12,3 +12,7 @@ prefix node-api
 # https://github.com/nodejs/node/issues/43457
 test_fatal/test_threads: PASS,FLAKY
 test_fatal/test_threads_report: PASS,FLAKY
+
+[$system==linux && $arch==ppc64]
+# https://github.com/nodejs/node/issues/59561
+test_sea_addon/test: SKIP

test/node-api/test_sea_addon/binding.c

@@ -0,0 +1,17 @@
+#include <node_api.h>
+#include <string.h>
+#include "../../js-native-api/common.h"
+
+static napi_value Method(napi_env env, napi_callback_info info) {
+  napi_value world;
+  const char* str = "world";
+  size_t str_len = strlen(str);
+  NODE_API_CALL(env, napi_create_string_utf8(env, str, str_len, &world));
+  return world;
+}
+
+NAPI_MODULE_INIT() {
+  napi_property_descriptor desc = DECLARE_NODE_API_PROPERTY("hello", Method);
+  NODE_API_CALL(env, napi_define_properties(env, exports, 1, &desc));
+  return exports;
+}

test/node-api/test_sea_addon/binding.gyp

@@ -0,0 +1,8 @@
+{
+  "targets": [
+    {
+      "target_name": "binding",
+      "sources": [ "binding.c" ]
+    }
+  ]
+}

test/node-api/test_sea_addon/test.js

@@ -0,0 +1,75 @@
+'use strict';
+// This tests that SEA can load addons packaged as assets by writing them to disk
+// and loading them via process.dlopen().
+const common = require('../../common');
+const { generateSEA, skipIfSingleExecutableIsNotSupported } = require('../../common/sea');
+
+skipIfSingleExecutableIsNotSupported();
+
+const assert = require('assert');
+
+const tmpdir = require('../../common/tmpdir');
+const { copyFileSync, writeFileSync, existsSync, rmSync } = require('fs');
+const {
+  spawnSyncAndExitWithoutError,
+  spawnSyncAndAssert,
+} = require('../../common/child_process');
+const { join } = require('path');
+const configFile = tmpdir.resolve('sea-config.json');
+const seaPrepBlob = tmpdir.resolve('sea-prep.blob');
+const outputFile = tmpdir.resolve(process.platform === 'win32' ? 'sea.exe' : 'sea');
+tmpdir.refresh();
+
+// Copy test fixture to working directory
+const addonPath = join(__dirname, 'build', common.buildType, 'binding.node');
+const copiedAddonPath = tmpdir.resolve('binding.node');
+copyFileSync(addonPath, copiedAddonPath);
+writeFileSync(tmpdir.resolve('sea.js'), `
+const sea = require('node:sea');
+const fs = require('fs');
+const path = require('path');
+
+const addonPath = path.join(process.cwd(), 'hello.node');
+fs.writeFileSync(addonPath, new Uint8Array(sea.getRawAsset('hello.node')));
+const mod = {exports: {}}
+process.dlopen(mod, addonPath);
+console.log('hello,', mod.exports.hello());
+`, 'utf-8');
+
+writeFileSync(configFile, `
+{
+  "main": "sea.js",
+  "output": "sea-prep.blob",
+  "disableExperimentalSEAWarning": true,
+  "assets": {
+    "hello.node": "binding.node"
+  }
+}
+`, 'utf8');
+
+spawnSyncAndExitWithoutError(
+  process.execPath,
+  ['--experimental-sea-config', 'sea-config.json'],
+  { cwd: tmpdir.path },
+);
+assert(existsSync(seaPrepBlob));
+
+generateSEA(outputFile, process.execPath, seaPrepBlob);
+
+// Remove the copied addon after it's been packaged into the SEA blob
+rmSync(copiedAddonPath, { force: true });
+
+spawnSyncAndAssert(
+  outputFile,
+  [],
+  {
+    env: {
+      ...process.env,
+      NODE_DEBUG_NATIVE: 'SEA',
+    },
+    cwd: tmpdir.path,
+  },
+  {
+    stdout: /hello, world/,
+  },
+);