repl: show proxies as Proxy objects

Fixes: nodejs#16483

Author: bnoordhuis

lib/repl.js

@@ -100,7 +100,9 @@ function hasOwnProperty(obj, prop) {
 
 // Can overridden with custom print functions, such as `probe` or `eyes.js`.
 // This is the default "writer" value if none is passed in the REPL options.
-exports.writer = util.inspect;
+const writer = exports.writer = (obj) => util.inspect(obj, writer.options);
+writer.options =
+    Object.assign(util.inspect.defaultOptions, { showProxy: true });
 
 exports._builtinLibs = internalModule.builtinLibs;
 
@@ -370,11 +372,10 @@ function REPLServer(prompt,
   }
   self.useColors = !!options.useColors;
 
-  if (self.useColors && self.writer === util.inspect) {
+  if (self.useColors && self.writer === writer) {
     // Turn on ANSI coloring.
-    self.writer = function(obj, showHidden, depth) {
-      return util.inspect(obj, showHidden, depth, true);
-    };
+    self.writer = (obj) => util.inspect(obj, self.writer.options);
+    self.writer.options = Object.assign(writer.options, { colors: true });
   }
 
   function filterInternalStackFrames(error, structuredStack) {

test/parallel/test-repl.js

@@ -412,6 +412,18 @@ function error_test() {
       expect: `${prompt_multiline}${prompt_multiline}undefined\n${prompt_unix}`
     },
 
+    // https://github.com/nodejs/node/issues/16483
+    {
+      client: client_unix, send: 'new Proxy({x:42}, {get(){throw null}});',
+      expect: `Proxy [ { x: 42 }, { get: [Function: get] } ]\n${prompt_unix}`
+    },
+    {
+      client: client_unix,
+      send: 'repl.writer.options.showProxy = false, new Proxy({x:42}, {});',
+      expect: `{ x: 42 }\n${prompt_unix}`
+    },
+
+
     // Newline within template string maintains whitespace.
     { client: client_unix, send: '`foo \n`',
       expect: `${prompt_multiline}'foo \\n'\n${prompt_unix}` },