util: handle symbols properly in format()

Currently, if util.format() is called with a string as its first
argument, and a Symbol as one of the subsequent arguments, an
exception is thrown due to an attempted implicit string conversion.
This commit causes Symbols to be explicitly converted.

Fixes: https://github.com/iojs/io.js/issues/927
PR-URL: https://github.com/iojs/io.js/pull/931
Reviewed-By: Domenic Denicola <domenic@domenicdenicola.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/test/parallel/test-util-format.js b/test/parallel/test-util-format.js
index 446e11e98d..7155094198 100644
--- a/test/parallel/test-util-format.js
+++ b/test/parallel/test-util-format.js
@@ -1,6 +1,7 @@
 var common = require('../common');
 var assert = require('assert');
 var util = require('util');
+var symbol = Symbol('foo');
 
 assert.equal(util.format(), '');
 assert.equal(util.format(''), '');
@@ -14,6 +15,15 @@ assert.equal(util.format('test'), 'test');
 // CHECKME this is for console.log() compatibility - but is it *right*?
 assert.equal(util.format('foo', 'bar', 'baz'), 'foo bar baz');
 
+// ES6 Symbol handling
+assert.equal(util.format(symbol), 'Symbol(foo)');
+assert.equal(util.format('foo', symbol), 'foo Symbol(foo)');
+assert.equal(util.format('%s', symbol), 'Symbol(foo)');
+assert.equal(util.format('%j', symbol), 'undefined');
+assert.throws(function() {
+  util.format('%d', symbol);
+}, TypeError);
+
 assert.equal(util.format('%d', 42.0), '42');
 assert.equal(util.format('%d', 42), '42');
 assert.equal(util.format('%s', 42), '42');