test: add test to verify ErrnoException path

This commit adds a test to verify that the path argument to
ErrnoException can contain UTF-8 characters.

PR-URL: #13958
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

test/addons/errno-exception/binding.cc

@@ -0,0 +1,18 @@
+#include <node.h>
+#include <v8.h>
+
+void Method(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  v8::Isolate* isolate = args.GetIsolate();
+  v8::HandleScope scope(isolate);
+  args.GetReturnValue().Set(node::ErrnoException(isolate,
+                                                10,
+                                                "syscall",
+                                                "some error msg",
+                                                "päth"));
+}
+
+void init(v8::Local<v8::Object> exports) {
+  NODE_SET_METHOD(exports, "errno", Method);
+}
+
+NODE_MODULE(binding, init)

test/addons/errno-exception/binding.gyp

@@ -0,0 +1,9 @@
+{
+  'targets': [
+    {
+      'target_name': 'binding',
+      'defines': [ 'V8_DEPRECATION_WARNINGS=1' ],
+      'sources': [ 'binding.cc' ]
+    }
+  ]
+}

test/addons/errno-exception/test.js

@@ -0,0 +1,15 @@
+'use strict';
+
+const common = require('../../common');
+
+// Verify that the path argument to node::ErrnoException() can contain UTF-8
+// characters.
+
+const assert = require('assert');
+const binding = require(`./build/${common.buildType}/binding`);
+const err = binding.errno();
+
+assert.strictEqual(err.syscall, 'syscall');
+assert.strictEqual(err.errno, 10);
+assert.strictEqual(err.path, 'päth');
+assert.ok(/^Error:\s\w+, some error msg 'päth'$/.test(err.toString()));