From d611f5ad3ed189db168820f4ff0fae3bc7afe7fa Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Fri, 5 Jul 2019 17:24:28 +0200
Subject: [PATCH] repl: fix some repl context issues

This partially fixes contexts like `{} instanceof Object === false`
in the REPL. This does not fix all cases, since it's something
fundamental from the REPL's design that things like these can happen.

Refs: https://github.com/nodejs/node/issues/27859

PR-URL: https://github.com/nodejs/node/pull/28561
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/repl.js                        |  7 +++++--
 test/parallel/test-repl-context.js | 10 ++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/lib/repl.js b/lib/repl.js
index ed0c9fd420fae3..2f82c2ca49fc71 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -875,8 +875,11 @@ REPLServer.prototype.createContext = function() {
       context = vm.createContext();
     });
     for (const name of Object.getOwnPropertyNames(global)) {
-      Object.defineProperty(context, name,
-                            Object.getOwnPropertyDescriptor(global, name));
+      // Only set properties on the context that do not exist as primordial.
+      if (!(name in primordials)) {
+        Object.defineProperty(context, name,
+                              Object.getOwnPropertyDescriptor(global, name));
+      }
     }
     context.global = context;
     const _console = new Console(this.outputStream);
diff --git a/test/parallel/test-repl-context.js b/test/parallel/test-repl-context.js
index 287d8adc295d7a..88bd47a9281a9c 100644
--- a/test/parallel/test-repl-context.js
+++ b/test/parallel/test-repl-context.js
@@ -16,11 +16,21 @@ const stream = new ArrayStream();
     useGlobal: false
   });
 
+  let output = '';
+  stream.write = function(d) {
+    output += d;
+  };
+
   // Ensure that the repl context gets its own "console" instance.
   assert(r.context.console);
 
   // Ensure that the repl console instance is not the global one.
   assert.notStrictEqual(r.context.console, console);
+  assert.notStrictEqual(r.context.Object, Object);
+
+  stream.run(['({} instanceof Object)']);
+
+  assert.strictEqual(output, 'true\n> ');
 
   const context = r.createContext();
   // Ensure that the repl context gets its own "console" instance.