test: add finalizer exception test

test/external.cc

@@ -51,13 +51,28 @@ Value GetFinalizeCount(const CallbackInfo& info) {
    return Number::New(info.Env(), finalizeCount);
 }
 
+Value CreateExternalWithFinalizeException(const CallbackInfo& info) {
+  return External<int>::New(info.Env(), new int(1),
+    [](Env env, int* data) {
+      Error error = Error::New(env, "Finalizer exception");
+      delete data;
+#ifdef NAPI_CPP_EXCEPTIONS
+      throw error;
+#else
+      error.ThrowAsJavaScriptException();
+#endif
+    });
+}
+
 } // end anonymous namespace
 
 Object InitExternal(Env env) {
   Object exports = Object::New(env);
 
   exports["createExternal"] = Function::New(env, CreateExternal);
   exports["createExternalWithFinalize"] = Function::New(env, CreateExternalWithFinalize);
+  exports["createExternalWithFinalizeException"] =
+      Function::New(env, CreateExternalWithFinalizeException);
   exports["createExternalWithFinalizeHint"] = Function::New(env, CreateExternalWithFinalizeHint);
   exports["checkExternal"] = Function::New(env, CheckExternal);
   exports["getFinalizeCount"] = Function::New(env, GetFinalizeCount);

test/external.js

@@ -1,12 +1,34 @@
 'use strict';
 const buildType = process.config.target_defaults.default_configuration;
 const assert = require('assert');
+const path = require('path');
+const { spawnSync } = require('child_process');
 const testUtil = require('./testUtil');
 
-test(require(`./build/${buildType}/binding.node`));
-test(require(`./build/${buildType}/binding_noexcept.node`));
+if (process.argv.length === 3) {
+  let x =
+    require(process.argv[2]).external.createExternalWithFinalizeException();
+  x = null;
 
-function test(binding) {
+  // Keep calling `global.gc()` until it throws.
+  const interval = setInterval(() => {
+    try {
+      global.gc();
+    } catch (anException) {
+      assert(!!anException.message.match(/Finalizer exception/));
+      clearInterval(interval);
+      process.exit(0);
+    }
+  }, 100);
+  return;
+}
+
+test(path.resolve(path.join(__dirname, `./build/${buildType}/binding.node`)));
+test(path.resolve(path.join(__dirname,
+  `./build/${buildType}/binding_noexcept.node`)));
+
+function test(bindingPath) {
+  const binding = require(bindingPath);
   testUtil.runGCTests([
     'External without finalizer',
     () => {
@@ -41,4 +63,9 @@ function test(binding) {
       assert.strictEqual(1, binding.external.getFinalizeCount());
     },
   ]);
+
+  const child = spawnSync(process.execPath, [
+    '--expose-gc', __filename, bindingPath
+  ], { stdio: 'inherit' });
+  assert(!child.signal && child.status === 0);
 }