[Fix] use util.inspect for a custom inspection symbol method

Node internal objects (like URL) expect options to be passed in to inspect call. Without these options inspecting some native objects will result in unexpected errors.

Author: martinheidegger

index.js

@@ -65,8 +65,9 @@ function addNumericSeparator(num, str) {
     return $replace.call(str, sepRegex, '$&_');
 }
 
-var inspectCustom = require('./util.inspect').custom;
-var inspectSymbol = inspectCustom && isSymbol(inspectCustom) ? inspectCustom : null;
+var utilInspect = require('./util.inspect');
+var inspectCustom = utilInspect.custom;
+var inspectSymbol = isSymbol(inspectCustom) ? inspectCustom : null;
 
 module.exports = function inspect_(obj, options, depth, seen) {
     var opts = options || {};
@@ -193,8 +194,8 @@ module.exports = function inspect_(obj, options, depth, seen) {
         return '{ [' + String(obj) + '] ' + $join.call(parts, ', ') + ' }';
     }
     if (typeof obj === 'object' && customInspect) {
-        if (inspectSymbol && typeof obj[inspectSymbol] === 'function') {
-            return obj[inspectSymbol]();
+        if (inspectSymbol && typeof obj[inspectSymbol] === 'function' && utilInspect) {
+            return utilInspect(obj, { depth: maxDepth - depth });
         } else if (customInspect !== 'symbol' && typeof obj.inspect === 'function') {
             return obj.inspect();
         }

test/inspect.js

@@ -100,3 +100,40 @@ test('maxStringLength', function (t) {
 
     t.end();
 });
+
+test('inspect options', { skip: !utilInspect.custom }, function (t) {
+    var obj = {};
+    obj[utilInspect.custom] = function () {
+        return JSON.stringify(arguments);
+    };
+    t.equal(
+        inspect(obj),
+        utilInspect(obj, { depth: 5 }),
+        'custom symbols will use node\'s inspect'
+    );
+    t.equal(
+        inspect(obj, { depth: 2 }),
+        utilInspect(obj, { depth: 2 }),
+        'a reduced depth will be passed to node\'s inspect'
+    );
+    t.equal(
+        inspect({ d1: obj }, { depth: 3 }),
+        '{ d1: ' + utilInspect(obj, { depth: 2 }) + ' }',
+        'deep objects will receive a reduced depth'
+    );
+    t.equal(
+        inspect({ d1: obj }, { depth: 1 }),
+        '{ d1: [Object] }',
+        'unlike nodejs inspect, customInspect will not be used once the depth is exceeded.'
+    );
+    t.end();
+});
+
+test('inspect URL', { skip: typeof URL === 'undefined' }, function (t) {
+    t.match(
+        inspect(new URL('https://nodejs.org')),
+        /nodejs\.org/, // Different environments stringify it differently
+        'url can be inspected'
+    );
+    t.end();
+});