Fix: update custom inspection to use a symbol

index.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var path = require('path');
+var util = require('util');
 var isBuffer = require('buffer').Buffer.isBuffer;
 
 var clone = require('clone');
@@ -157,6 +158,11 @@ File.prototype.inspect = function() {
   return '<File ' + inspect.join(' ') + '>';
 };
 
+// Newer Node.js versions use this symbol for custom inspection.
+if (util.inspect.custom) {
+  File.prototype[util.inspect.custom] = File.prototype.inspect;
+}
+
 File.isCustomProp = function(key) {
   return builtInFields.indexOf(key) === -1;
 };

test/file.js

@@ -2,6 +2,7 @@
 
 var fs = require('fs');
 var path = require('path');
+var util = require('util');
 var expect = require('expect');
 var miss = require('mississippi');
 var cloneable = require('cloneable-readable');
@@ -746,7 +747,12 @@ describe('File', function() {
 
     it('returns correct format when no contents and no path', function(done) {
       var file = new File();
-      expect(file.inspect()).toEqual('<File >');
+      var expectation = '<File >';
+      expect(file.inspect()).toEqual(expectation);
+      expect(util.inspect(file)).toEqual(expectation);
+      if (util.inspect.custom) {
+        expect(file[util.inspect.custom]()).toEqual(expectation);
+      }
       done();
     });