From 5a2cc3af8a7848dc0eed81445af79b1eb1409b81 Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Wed, 12 Dec 2018 00:25:32 +0100
Subject: [PATCH] util: inspect all prototypes

It is currently difficult to distinguish multiple objects from each
other because the prototype is not properly inspected. From now on
all prototypes will be inspected, even if we do not fully know how
they will look like / what their shape really is.

Fixes: https://github.com/nodejs/node/issues/24917
---
 lib/internal/util/inspect.js       | 13 +++++++------
 test/parallel/test-util-inspect.js | 21 ++++++++++++++++++---
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js
index 6ec27b9d1d9c05..c7bb9b324f6143 100644
--- a/lib/internal/util/inspect.js
+++ b/lib/internal/util/inspect.js
@@ -322,7 +322,7 @@ function getEmptyFormatArray() {
   return [];
 }
 
-function getConstructorName(obj) {
+function getConstructorName(obj, ctx) {
   let firstProto;
   while (obj) {
     const descriptor = Object.getOwnPropertyDescriptor(obj, 'constructor');
@@ -341,10 +341,11 @@ function getConstructorName(obj) {
   if (firstProto === null) {
     return null;
   }
-  // TODO(BridgeAR): Improve prototype inspection.
-  // We could use inspect on the prototype itself to improve the output.
 
-  return '';
+  return `<${inspect(firstProto, {
+    ...ctx,
+    customInspect: false
+  })}>`;
 }
 
 function getPrefix(constructor, tag, fallback) {
@@ -503,7 +504,7 @@ function formatValue(ctx, value, recurseTimes) {
   }
 
   if (ctx.stop !== undefined) {
-    const name = getConstructorName(value) || value[Symbol.toStringTag];
+    const name = getConstructorName(value, ctx) || value[Symbol.toStringTag];
     return ctx.stylize(`[${name || 'Object'}]`, 'special');
   }
 
@@ -547,7 +548,7 @@ function formatValue(ctx, value, recurseTimes) {
 function formatRaw(ctx, value, recurseTimes) {
   let keys;
 
-  const constructor = getConstructorName(value);
+  const constructor = getConstructorName(value, ctx);
   let tag = value[Symbol.toStringTag];
   if (typeof tag !== 'string')
     tag = '';
diff --git a/test/parallel/test-util-inspect.js b/test/parallel/test-util-inspect.js
index c0fc3219ce736f..66cd8e2e1d38c9 100644
--- a/test/parallel/test-util-inspect.js
+++ b/test/parallel/test-util-inspect.js
@@ -1738,19 +1738,34 @@ assert.strictEqual(
   );
 }
 
-// Manipulate the prototype to one that we can not handle.
+// Manipulate the prototype in weird ways.
 {
   let obj = { a: true };
   let value = (function() { return function() {}; })();
   Object.setPrototypeOf(value, null);
   Object.setPrototypeOf(obj, value);
-  assert.strictEqual(util.inspect(obj), '{ a: true }');
+  assert.strictEqual(util.inspect(obj), '<[Function]> { a: true }');
+  assert.strictEqual(
+    util.inspect(obj, { colors: true }),
+    '<\u001b[36m[Function]\u001b[39m> { a: \u001b[33mtrue\u001b[39m }'
+  );
 
   obj = { a: true };
   value = [];
   Object.setPrototypeOf(value, null);
   Object.setPrototypeOf(obj, value);
-  assert.strictEqual(util.inspect(obj), '{ a: true }');
+  assert.strictEqual(
+    util.inspect(obj),
+    '<[Array: null prototype] []> { a: true }'
+  );
+
+  function StorageObject() {}
+  StorageObject.prototype = Object.create(null);
+  assert.strictEqual(
+    util.inspect(new StorageObject()),
+    '<[Object: null prototype] {}> {}'
+  );
+
 }
 
 // Check that the fallback always works.