[New] add enumerable own Symbols to plain object output

Author: ljharb

index.js

@@ -15,7 +15,9 @@ var objectToString = Object.prototype.toString;
 var functionToString = Function.prototype.toString;
 var match = String.prototype.match;
 var bigIntValueOf = typeof BigInt === 'function' ? BigInt.prototype.valueOf : null;
+var gOPS = Object.getOwnPropertySymbols;
 var symToString = typeof Symbol === 'function' ? Symbol.prototype.toString : null;
+var isEnumerable = Object.prototype.propertyIsEnumerable;
 
 var inspectCustom = require('./util.inspect').custom;
 var inspectSymbol = inspectCustom && isSymbol(inspectCustom) ? inspectCustom : null;
@@ -380,5 +382,13 @@ function arrObjKeys(obj, inspect) {
             xs.push(key + ': ' + inspect(obj[key], obj));
         }
     }
+    if (typeof gOPS === 'function') {
+        var syms = gOPS(obj);
+        for (var j = 0; j < syms.length; j++) {
+            if (isEnumerable.call(obj, syms[j])) {
+                xs.push('[' + inspect(syms[j]) + ']: ' + inspect(obj[syms[j]], obj));
+            }
+        }
+    }
     return xs;
 }

test/inspect.js

@@ -21,7 +21,25 @@ test('inspect custom symbol', { skip: !hasSymbols || !utilInspect || !utilInspec
 
     t.equal(inspect([obj, []]), '[ ' + (utilInspect.custom ? 'symbol' : 'string') + ', [] ]');
     t.equal(inspect([obj, []], { customInspect: true }), '[ ' + (utilInspect.custom ? 'symbol' : 'string') + ', [] ]');
-    t.equal(inspect([obj, []], { customInspect: false }), '[ { inspect: [Function: stringInspect] }, [] ]');
+    t.equal(
+        inspect([obj, []], { customInspect: false }),
+        '[ { inspect: [Function: stringInspect]' + (utilInspect.custom ? ', [' + inspect(utilInspect.custom) + ']: [Function: custom]' : '') + ' }, [] ]'
+    );
+});
+
+test('symbols', { skip: !hasSymbols }, function (t) {
+    t.plan(2);
+
+    var obj = { a: 1 };
+    obj[Symbol('test')] = 2;
+    obj[Symbol.iterator] = 3;
+    Object.defineProperty(obj, Symbol('non-enum'), {
+        enumerable: false,
+        value: 4
+    });
+
+    t.equal(inspect(obj), '{ a: 1, [Symbol(test)]: 2, [Symbol(Symbol.iterator)]: 3 }', 'object with symbols');
+    t.equal(inspect([obj, []]), '[ { a: 1, [Symbol(test)]: 2, [Symbol(Symbol.iterator)]: 3 }, [] ]', 'object with symbols');
 });
 
 test('maxStringLength', function (t) {