repl: Enable tab completion for global properties

When `useGlobal` is false, tab completion in the repl does not enumerate
global properties. Instead of just setting these properties blindly on
the global context, e.g.

    context[prop] = global[prop]

Use `Object.defineProperty` and the property descriptor found on
`global` for the new property in `context`.

Also addresses a previously unnoticed issue where `console` is writable
when `useGlobal` is false.

If the binary has been built with `./configure --without-intl` then the
`Intl` builtin type will not be available in a repl runtime. Check for
this in the test.

Fixes: https://github.com/nodejs/node/issues/7353
PR-URL: https://github.com/nodejs/node/pull/7369
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 26 insertions, 0 deletions

diff --git a/test/parallel/test-repl-context.js b/test/parallel/test-repl-context.js
new file mode 100644
index 0000000000..1b319a036f
--- /dev/null
+++ b/test/parallel/test-repl-context.js
@@ -0,0 +1,26 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const repl = require('repl');
+
+// Create a dummy stream that does nothing
+const stream = new common.ArrayStream();
+
+// Test when useGlobal is false
+testContext(repl.start({
+  input: stream,
+  output: stream,
+  useGlobal: false
+}));
+
+function testContext(repl) {
+  const context = repl.createContext();
+  // ensure that the repl context gets its own "console" instance
+  assert(context.console instanceof require('console').Console);
+
+  // ensure that the repl's global property is the context
+  assert(context.global === context);
+
+  // ensure that the repl console instance does not have a setter
+  assert.throws(() => context.console = 'foo');
+}